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Mothers should wait at least a year between giving birth and getting pregnant again to reduce health risks to mother and baby, a new study says.

But researchers say they need not wait as long as the 18 months recommended in the current World Health Organization guidelines.

Small gaps between pregnancies risk premature births, smaller babies and infant and mother mortality.

The researchers hope the findings will be "reassuring" for older women.

Senior study author Dr Wendy Norman said it was "encouraging news" for women over 35 who were planning their families.

"Older mothers for the first time have excellent evidence to guide the spacing of their children," she said.

"Achieving that optimal one-year interval should be doable for many women and is clearly worthwhile to reduce complication risks."

The study, of nearly 150,000 births in Canada, by University of British Columbia (UBC) and the Harvard TH Chan School of Public Health is published in JAMA Internal Medicine.

The study found 12-to-18 months was the ideal length of time between giving birth and becoming pregnant again.

Current World Health Organization guidelines recommend an ideal interval of 24 months and no fewer than 18 months.

The researchers also found:

Getting pregnant less than 12 months after giving birth was associated with risks for women for all ages

There were risks to the mother only for women over the age of 35, while risks to the infant were found for all women, but were greatest for those aged between 20 and 34

Women over 35 who conceived six months after a previous birth had a 1.2% risk of maternal mortality or harm (12 cases per 1,000 pregnancies)

Waiting 18 months between pregnancies reduced the risk to 0.5% (five cases per 1,000)

Younger women who got pregnant six months after a previous birth had an 8.5% risk (85 cases per 1,000) of premature labour

This dropped to 3.7% (37 per 1,000) if they waited 18 months between pregnancies

The study's lead author, Laura Schummers, said: "Our study found increased risks to both mother and infant when pregnancies are closely spaced, including for women older than 35.

"The findings for older women are particularly important, as older women tend to more closely space their pregnancies and often do so intentionally."

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The study looked at only one population of women - in Canada - so it is unclear how applicable this would be worldwide.

Researcher Dr. Sonia Hernandez-Diaz said the findings suggested different risks for each age group.

"Short pregnancy spacing might reflect unplanned pregnancies, particularly among young women.

"Whether the elevated risks are due to our bodies not having time to recover if we conceive soon after delivering or to factors associated with unplanned pregnancies, like inadequate prenatal care, the recommendation might be the same: improve access to postpartum contraception, or abstain from unprotected sexual intercourse with a male partner following a birth."

Mandy Forrester, from the Royal College of Midwives, said the study was "useful research and builds on previous research into birth spacing".

"Ultimately, it will be a woman's choice, whatever age they are, about how long they leave between their pregnancies. What is important is that they are aware of the evidence around birth spacing and that they make their choice armed with the right information.

"Health professionals will always support a woman in her choice, which will be about what is right for them and their pregnancy.

She said women needed access to contraceptive advice to allow them to space their births, if that was their choice, but said in specialist family planning service provision in the UK was "patchy, with GPs frequently offering only oral contraception".

"Specialist services should be available for all women."</s>
• Women have long been told to wait at least 18 months between giving birth and becoming pregnant again, but a new study suggests a year is long enough.
• Having an interpregnancy interval of under 12 months, however, can lead to complications for both mother and baby.
• Mothers aged over 35 who become pregnant again after less than a year are more likely to put their own health at risk than younger women.
• However, researchers hope the findings will provide hope for older mothers worrying about their “biological clock.”

Women are often told that their fertility will drop off a cliff once they hit their mid-30s, meaning the notion of a “ticking biological clock” is well ingrained in the minds of many.

While the accuracy of this concept is often disputed, it’s not uncommon for couples to have children in close succession when the mother is over the age of 35, to ensure they have the best chances of conceiving and having a healthy pregnancy.

Current World Health Organisation (WHO) guidelines recommend mothers wait at least 18 months (and ideally 24) before getting pregnant again after giving birth, but an encouraging new study suggests waiting just a year may actually be enough.

According to the study of nearly 150,000 births in Canada, carried out by the University of British Columbia (UBC) and the Harvard TH Chan School of Public Health, 12 months is enough time to wait to ensure there is no great risk of premature birth, smaller babies, or infant and mother mortality.

The study confirmed, however, that becoming pregnant less than a year after giving birth would indeed put babies at risk of health problems.

For younger mothers, short interpregnancy intervals pose a greater risk to the baby – women aged between 20 and 34 who conceived six months after giving birth had an 8.5% risk of giving birth prematurely, while waiting 18 months decreased this risk to 3.7%.

Meanwhile, women aged over 35 were found to be more likely than younger mothers to experience complications with their own health if their interpregnancy interval was less than a year.

Older women who waited just six months before conceiving again were found to have a 1.2% risk of maternal mortality or harm, while the risk decreased to 0.5% if they waited 18 months.

“Older mothers for the first time have excellent evidence to guide the spacing of their children,” said senior study author Dr Wendy Norman.

“Achieving that optimal one-year interval should be doable for many women and is clearly worthwhile to reduce complication risks.”

The researchers say that 12-18 months is the ideal gap.

“Older women need to weigh the risks to their own health and their infants’ health against the risks of not achieving the number of children they want,” commented Dr Stephanie B Teal of the University of Colorado School of Medicine’s Department of Obstetrics and Gynecology.

“Simply telling older women to delay conception is not likely to improve health outcomes, as women are aware of their ‘biological clocks’ and many will value their desire for another child over their physician’s warnings.”

Mandy Forrester, Head of Quality and Standards at the Royal College of Midwives, says that ultimately, when a woman becomes pregnant should be her choice, but the new research could help people make informed decisions.

“It will be a woman’s choice whatever age they are about how long they leave between their pregnancies,” she said in a statement.

“What is important is that they are aware of the evidence around birth spacing and that they make their choice armed with the right information. Health professionals will always support a woman in her choice, which will be about what is right for them and their pregnancy.”</s>New parents planning another pregnancy should wait at least a year to conceive in order to minimize health risks to both mom and baby, according to new research from the University of British Columbia (UBC) and the Harvard T.H. Chan School of Public Health.

Although public health agencies, including the World Health Organization, generally recommend at least 18 months to two years between pregnancies, the study published in the journal JAMA Internal Medicine suggests one year after birth could be enough time before safely conceiving again for women who are anxious to have another child as soon as possible.

"The very lowest risk time that we found was 18 months," said Laura Schummers, lead author and a postdoctoral fellow at UBC's department of family practice. "But what we found also was that risks between 12 and 24 months were basically equivalent to those at 18 months."

The risks Schummers and her team evaluated for women are often called "near-miss mortality" events associated with pregnancy and delivery, she said. "This is organ failure, intubation, or being in [the] intensive care unit. This is not ... a complication like developing preeclampsia, which is much more common."

The research team also included maternal deaths, but those are "thankfully" extremely rare in Canada, she said, so were too few to be considered on their own.

The severe fetal and newborn risks measured include very low birth weight, premature birth, stillbirth and infant death within one year of birth.

The researchers looked for these outcomes in records documenting 148,544 pregnancies in British Columbia over 10 years, from 2004 to 2014. They also tracked the age range of the pregnant women to see if those age 35 and over might be at heightened risk.

The study found that the risk of these serious health issues — for both the infant and mother — was higher when women had conceived six months after previously giving birth compared to waiting at least 12 to 18 months.

Among women between 20 and 34 years old who became pregnant six months after their last baby was born, 85 out of 1,000 had premature births. That risk dropped by more than half (37 cases per 1,000) when the pregnancies were spaced out by 18 months.

Although being older didn't increase that risk for infants any further, it did affect affect the mothers themselves. About six out of every 1,000 women age 35 and older who conceived another baby six months after giving birth suffered life-threatening complications. That risk dropped to about three in 1,000 when mothers in that age group waited at least a year.

"A family that might be considering a second pregnancy about six or nine months after delivery of the first, it might be worth waiting that extra three to six months to lower risks, both to the mother and baby," said Schummers.

The study purposely separated women out into age groups, she said, because women over age 35 may feel "time pressure" to have a second child quickly as fertility decreases.

But the findings could actually be "encouraging" for those women, Schummers said, by showing that it might not be necessary to wait for 18 months, as other health guidelines suggest, and a year might seem more manageable.

Dr. Danielle Martin, a family physician at Women's College Hospital in Toronto, said the study could help health-care providers "get a little bit more specific about, how long should women be trying to wait between giving birth and their next conception, all things being equal, if they want to minimize the health risks for themselves and their babies."

The severe risks considered by the researchers are "very rare," noted Martin, who was not involved in the study.

"A small increase in an extremely rare event is still an extremely rare event, but nevertheless it is an increase in the risk," she said. "And I think that women need to know, and their partners need to know ... that it is one of many factors that they may want to consider."

'Not every pregnancy is planned'

Those other factors could include the timing that works best for them and their families, as well as career considerations, Martin said. Women and their partners are also trying to balance the risks of having another child quickly with the risks of waiting as they continue to age.

It's also important to remember that "not every pregnancy is planned," she added. "We are always going to need to continue to try to find other ways to reduce the risk for women who do get pregnant in less than 12 months after giving birth."

"There's a lot that we don't know" about what exactly happens biologically that would make it more risky to have pregnancies less than a year apart, Martin said.

"Still much work remains to be done."

Watch this story on The National:</s>New mums are urged to wait a year before getting pregnant again, a new study suggests.

A gap of 12 to 18 months will make the pregnancy safer for both the mother and the child.

This is particularly important for older mums who might try to have several children in a short period of time before their fertility declines, the Irish Daily Mail reports.

A gap of less than 12 months between pregnancies was the most dangerous, and increased the risk of maternal death, premature birth, stillbirth, and low birth weight, Harvard experts found.

Dr Laura Schumers, study leader, said: “Our study found increased risks to both mother and infant when pregnancies are closely spaced.”

The study, which was published in JAMA Internal Medicine, analysed 148,500 Canadian pregnancies over a decade and found that waiting for 12 to 18 months reduced the risks substantially after which they gradually rose again.

Experts believe a short gap between pregnancies doesn’t give the body enough time to recover but leaving it for too long might bring the risk of complications associated with an ageing mother.

In 2017 an average Irish woman was giving birth to their first child at the age of 31, according to CSO data.

For women over the age of 35, the short gap was dangerous for the mother herself.

But for younger women, there was an increased risk of the baby being born prematurely.

There was a 1.2% risk of maternal death for women over 35 who conceived six months after a previous birth.

The risk went down to 0.5% after an 18 month wait.

For younger women, the risk of a premature birth (delivery before 37 weeks) was around 8.5% with a gap of six months between pregnancy, which dropped to 3.7% with an 18-month gap.

For women over 35, the risk of preterm birth was 6% for a six-month gap and 3.4% for a 18-month gap.

Mandy Forrester of the Royal College of Midwives said: “It will be a woman’s choice about how long they leave between their pregnancies.

“What is important is that they are aware of the evidence.”</s>Couples should wait at least a year after their baby is born before trying for another child, a major study suggests.

A gap of 12-to-18 months between pregnancies was shown to be the safest for both mother and child, Harvard scientists found.

Experts said last night the findings are particularly important for older mothers, who tend to try to have several children in a short period to complete their family before their fertility declines.

The study, which analysed 148,500 Canadian pregnancies in the space of a decade, found a gap of less than 12 months was the most dangerous - increasing the risk of maternal death, premature birth, stillbirth and low birth weight.

Study leader Dr Laura Schummers, whose findings are published in the JAMA Internal Medicine journal, said: ‘Our study found increased risks to both mother and infant when pregnancies are closely spaced, including for women older than 35.

‘The findings for older women are particularly important, as older women tend to more closely space their pregnancies and often do so intentionally.’

The researchers found the risks were different according to a woman’s age.

For those over 35, a short gap between pregnancies was particularly dangerous for the mother herself.

For younger women, the risk to the mother of a short gap between pregnancies was negligible, but there was an increased risk of the baby being born premature.

Among women over 35 who conceived six months after a previous birth, the researchers found a 1.2 per cent risk of maternal death or severe harm.

If they waited 18 months between pregnancies, the risk was more than halved to 0.5 per cent.

For younger women, a six-month gap between pregnancies resulted in an 8.5 per cent risk of preterm birth - delivery before 37 weeks - which dropped to 3.7 per cent with an 18-month gap.

Among over-35s, the preterm birth risk is six per cent for a six-month gap and 3.4 per cent for an 18-month wait.

Fellow researcher Dr Wendy Norman, of the University of British Columbia, said the findings provide the first ‘excellent evidence’ to help women guide the spacing of their children.

‘Achieving that optimal one-year interval should be doable for many women, and is clearly worthwhile to reduce complication risks,’ she said.

Scientists believe a short gap between pregnancies does not leave the body enough time to recover.

On the other hand, leaving it too long brings the risk of complications associated with an ageing mother.

Researcher Professor Sonia Hernandez-Diaz, of the Harvard T.H. Chan School of Public Health, added: ‘Whether the elevated risks are due to our bodies not having time to recover if we conceive soon after delivering or to factors associated with unplanned pregnancies, like inadequate prenatal care, the recommendation might be the same - improve access to postpartum contraception, or abstain from unprotected sexual intercourse with a male partner following a birth.’

Experts from the University of Colorado, writing a linked editorial piece in the same journal, said women increasingly feel under pressure to leave shorter gaps between pregnancies, because so many are having their first child at an older age.

‘Because the mean desired number of children US women is 2.6 and fertility declines rapidly in the late 30s and early 40s, women having a child when they are older than 35 years are likely to plan to have their next child soon thereafter,' they wrote.

That picture is mirrored in the UK, where the number of older mothers has soared in recent decades, as more women concentrate on their career first and turn to family later.

Women in this country now have their first child five years later on average than they did 40 years ago.

The average age of first-time motherhood in England and Wales is 28.8, according to the latest figures from 2016, up from 23.5 in 1970.</s>Women and their babies face health risks when there’s less that 12 months between the birth of one child and the conception of the next, according to a new study.

The researchers found a modest increase in risk of death or serious illness in the mother in intervals of less than 12 months and larger increases in the risk of adverse outcomes for the baby both before and after birth, as well as spontaneous preterm delivery.

Guidelines from the World Health Organization suggest that women wait at least two years before becoming pregnant again. The American College of Obstetricians and Gynecologists suggests that women should be advised to avoid interpregnancy periods of less than six months and “should be counseled on the risks and benefits of repeat pregnancy sooner than 18 months.”

The authors noted that the study found a shorter optimal interval between pregnancies than previously thought for all women. “The finding may be reassuring particularly for older women who must weigh the competing risks of increasing maternal age” with the risks of time between pregnancies, they wrote.

The study, published Monday in the journal JAMA Internal Medicine, included 123,122 women and 148,544 pregnancies, and it looked at how the health risks were applied to pregnant women of different ages. The participants were found using population health databases in Canada, which included all women who had at least two consecutive single pregnancies in a 10-year period.

For those 35 and over, the risk of maternal mortality and severe morbidity was 0.62% when there were only six months between the birth of one child and the conception of the next and 0.26% at 18 months. For mothers between 20 and 34, there was a predicted risk of 0.23% at six months and 0.25% at 18 months.

However, younger mothers had a higher risk of spontaneous preterm delivery with shorter interpregnancy intervals — 5.3% at six months and 3.2% at 18 months — and adverse fetal and infant outcomes — 2.0% predicted risk at six months, compared with 1.4% at 18 months — than older women.

This breakdown is relevant because the age at which American women are having their first child is increasing, due to changes in society and workplaces, according to the authors of an editorial published alongside the study.

“It’s a fairly common question that comes up now, because for people like me who see a lot of patients who are 40 having their first baby, the first question generally if we get through it unscathed is, ‘when can I have my next one?’ ” said Dr. Laura Riley, chair of obstetrics and gynecology at Weill Cornell Medicine and New York-Presbyterian, who was not involved with the research.

She said one of the strengths of the study is that it looked at the ages of women in relation to the risks, along with the size of the study population.

“My main takeaway is that this association between short interpregnancy interval and poor pregnancy outcome is well-known, but this shows that it’s for all maternal ages,” she said. “It doesn’t matter if you’re 20 or you’re 40.”

The authors of the study also attempted to account for other factors that could lead to poor pregnancy outcomes, such as whether the pregnancy was intended and whether the mother lived in a rural area.

The research considers possible health problems for both the mother and the baby, where previous data has been more focused on fetal health, according to Riley.

“They had maternal mortality and severe morbidity, which I think is another important piece of information, because a lot of times, people are focused on the baby, and they forget that there is some untoward maternal outcomes, as well,” she said.

Even though the risk of short interpregnancy intervals is present for all women, such short intervals will often be planned with older women, according to the editorial, due to their fertility and desired number of children.

“Clinicians should use patient-centered counseling and shared decision-making strategies that respect women’s desires for pregnancy, possibly at short intervals in women 35 years or older,” they said.

Although Riley tells mothers that it is ideal to wait a year before becoming pregnant again, she understands that age could play a part in a mother’s decision.

“I think the conversation needs to be that there is data to suggest that a short interpregnancy interval increases poor pregnancy outcomes, and so people will make decisions based on that information, but at least we can still have that discussion,” she said.</s>COUPLES should wait for at least a year after a baby is born before trying for their next child, a major study suggests.

A gap of 12 to 18 months between pregnancies was shown to be the safest for both mother and child, Harvard scientists found.

Experts said the findings are particularly important for older mothers, who tend try to have several children in a short period, to complete their family before their fertility declines.

The study, which analysed 148,500 Canadian pregnancies over a decade, found a gap of less than 12 months was the most dangerous — increasing the risk of maternal death, premature birth, stillbirth and low birth weight.

Waiting for 12 to 18 months was the safest option, after which the risks very gradually rose again.

Study leader Dr Laura Schummers, whose findings are published in JAMA Internal Medicine, said: “Our study found increased risks to both mother and infant when pregnancies are closely spaced.”

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The risks are different according to a woman’s age. For those over 35, a short gap was particularly dangerous for the mother herself. For younger women, the risk to the mother was negligible, but there was an increased chance of the baby being born prematurely. Among women over 35 who conceived six months after a previous birth, the researchers found a 1.2 per cent risk of maternal death or severe harm. After a wait of 18 months the risk dropped by more than half, to 0.5 per cent.

For younger women, a six-month gap between pregnancies resulted in an 8.5 per cent risk of preterm birth — delivery before 37 weeks — which dropped to 3.7 per cent with an 18-month gap. Among over-35s, the preterm birth risk was 6 per cent for a six-month gap, and 3.4 per cent for an 18-month wait.

Researcher Dr Wendy Norman, of the University of British Columbia, said the “one-year interval is clearly worthwhile”.

Scientists believe a short time between pregnancies does not leave the body enough time to recover. Leaving it too long brings the risk of complications associated with an ageing mother.

Experts from the University of Colorado, writing in the same journal, said women increasingly feel pressure to leave shorter gaps between pregnancies because they are starting families at an older age and know their fertility will decline.

That trend is mirrored in the UK, as more women focus on their career before having children. In 2016 the average age of a first-time mother in England and Wales was 28.8 — up from 23.5 in 1970. Mandy Forrester of the Royal College of Midwives said: “It will be a woman’s choice about how long they leave between their pregnancies. What is important is that they are aware of the evidence.”

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FIND OUT MORE HERE ►</s>Two pregnancies within six months of each other can cause rare, but serious, complications for the mother.

Women should wait a year between pregnancies to avoid potentially life-threatening complications for both the baby and the mother, according to new research from the University of British Columbia (UBC) and the Harvard T.H. Chan School of Public Health.

Most women consider a variety of factors when spacing out their pregnancies — their financial situation, their readiness for another baby, the dynamics within their own families, and so on. But an equally-important factor to consider is how soon the body is ready to carry and deliver another baby. There are health implications for both the mother and the baby that must factor into the decision, according to established research.

For years, the conventional wisdom has been that women should wait 18 months to two years between pregnancies, according to CBC News. Now, however, new research published in the Journal of the American Medical Association says that waiting only a year between pregnancies is enough to ward off the likely complications that could come from having pregnancies too close together.

Laura Schummers, the study’s lead author, says that she and her team — in looking at the data — saw several risks that could be most fully mitigated by waiting 18 to 24 months. But those same risks could be mitigated by waiting only 12 months, as well.

What The Data Says

Looking at the records of 148,544 pregnancies in British Columbia over 10 years — between 2004 and 2014 — Dr. Schummers and her team found that women who wait as little as six months were more at-risk for rare, but severe and life-threatening, complications during pregnancy and birth than women who waited longer.

Premature Birth: Among women between 20 and 34 years old who became pregnant six months after their last baby was born, 85 out of 1,000 of their babies were born prematurely. However, among women in the same age group who waited a year or more between pregnancies, only 37 out of 1,000 babies were born premature.

Deadly Risks For The Mother: Similarly, according to Fox News, “older women” (that is, women over 35) who spaced their pregnancies less than 12 months apart were at a greater risk of needing blood transfusions, of being put on a ventilator, or of organ failure. Women in both age groups who waited longer had a comparatively lower chance of developing those complications.

That they don’t have to wait 18 months to two years between pregnancies is good news for many women. Some women, for example, may belong to cultural communities that value women having many children. Women who wait until later in life to have kids — say, until their mid-30’s — can also take comfort in the news, by being able to have more pregnancies in their remaining fertility window.

Still, says Dr. Schummer, much work remains to be done. Doctors still don’t fully understand why a second pregnancy less than a year before the most recent is biologically risky — and more research is always needed.</s>Twelve to 18 months seems to be the ideal length of time between giving birth and getting pregnant again, according to new research from the University of British Columbia and the Harvard T.H. Chan School of Public Health.

In a study published Oct. 29 in JAMA Internal Medicine, researchers found that getting pregnant less than 12 months after delivery is associated with risks for women of all ages. Risks to the mother were found only for women over the age of 35, while risks to the infant were found for all women, but were greatest for women between the ages of 20-34.

"Our study found increased risks to both mother and infant when pregnancies are closely spaced, including for women older than 35," said the study's lead author Laura Schummers, a postdoctoral fellow in the UBC department of family practice who carried out the study as part of her dissertation at the Harvard T.H. Chan School of Public Health. "The findings for older women are particularly important, as older women tend to more closely space their pregnancies and often do so intentionally."

The study is the most extensive evaluation of how the role of pregnancy spacing could be impacted by maternal age. It is also the first investigation of pregnancy spacing and maternal mortality or severe morbidity--rare but life-threatening complications of pregnancy, labour and delivery--in a high-income country.

For the study, researchers examined the relationship between risks for mothers and babies associated with pregnancy spacing among 148,544 pregnancies in B.C. The data was pulled together from birth records, billing codes, hospitalization data, prescription data for infertility information, and census records.

Among women over 35 who conceived six months after a previous birth, the researchers found a 1.2 per cent risk (12 cases per 1,000 pregnancies) of maternal mortality or severe morbidity. Waiting 18 months between pregnancies, however, reduced the risk to 0.5 per cent (five cases per 1,000 pregnancies).

For younger women, the researchers found an 8.5 per cent risk (85 cases per 1,000 pregnancies) of spontaneous preterm birth--delivery before 37 weeks of pregnancy after labour that started on its own, for pregnancies spaced at six months. For younger women who waited 18 months between pregnancies, however, the risk dropped to 3.7 per cent (37 cases per 1,000 pregnancies).

Among older women, the risk of spontaneous preterm labour was about six per cent (60 cases per 1,000 pregnancies) at the six-month interval, compared to 3.4 per cent (34 cases per 1,000 pregnancies) at the 18-month interval.

Although the causes of poor pregnancy outcomes at short intervals among older and younger women were not examined in this study, the findings suggest different risk profiles for each age group.

"Short pregnancy spacing might reflect unplanned pregnancies, particularly among young women," said Dr. Sonia Hernandez-Diaz, professor of epidemiology at the Harvard T.H. Chan School of Public Health. "Whether the elevated risks are due to our bodies not having time to recover if we conceive soon after delivering or to factors associated with unplanned pregnancies, like inadequate prenatal care, the recommendation might be the same: improve access to postpartum contraception, or abstain from unprotected sexual intercourse with a male partner following a birth."

Senior author Dr. Wendy Norman, associate professor in the UBC department of family practice, said these findings of a shorter optimal interval are encouraging for women over 35 who are planning their families.

"Older mothers for the first time have excellent evidence to guide the spacing of their children," said Norman. "Achieving that optimal one-year interval should be doable for many women, and is clearly worthwhile to reduce complication risks."</s>New mothers who become pregnant less than a year after giving birth could be putting themselves and their unborn child at increased risk, a study has suggested.

Researchers who looked into nearly 150,000 births in Canada said those who waited 12 to 18 months to conceive after having a baby reduced the risk of short- and long-term damage to both the mother and child's health.

The study, by the University of British Columbia (UBC) and the Harvard TH Chan School of Public Health, found a short gap between pregnancies affected mothers aged over 35, while risks to the infant were found for all women - particularly for those aged 20 to 34.

Laura Schummers, a post-doctoral fellow at the UBC, said: "Our study found increased risks to both mother and infant when pregnancies are closely spaced, including for women older than 35.

"The findings for older women are particularly important, as older women tend to more closely space their pregnancies and often do so intentionally."

The study is the described by the authors as the "most extensive evaluation of how the role of pregnancy spacing could be impacted by maternal age".

It is also the first investigation of pregnancy spacing and maternal mortality or severe morbidity - rare but life-threatening complications of pregnancy, labour and delivery - in a high-income country, the authors said.

Among women over 35 who conceived six months after a previous birth, the researchers found a 1.2% risk of maternal mortality or severe morbidity. Waiting 18 months between pregnancies, however, reduced the risk to 0.5%, the authors said.

For younger women, the researchers found an 8.5% risk of spontaneous preterm birth - delivery before 37 weeks of pregnancy after labour that started on its own - for pregnancies spaced at six months.

For younger women who waited 18 months between pregnancies, however, the risk dropped to 3.7per cent.

Senior author Dr Wendy Norman, UBC associate professor, said: "Achieving that optimal one-year interval should be doable for many women, and is clearly worthwhile to reduce complication risks."
Research published in JAMA Internal Medicine describes that mothers should wait at least a year between giving birth and getting pregnant again to reduce health risks to mother and baby.