Malnutrition, maternal depression, and maternal substance use are three of these factors which have received particular attention by researchers, however, many more factors have been considered. Postnatal depression Although there are a large number of studies contemplating the effect of maternal depression and postnatal depression of various areas of infant development, they are yet to come to a consensus regarding the true effects. There are numerous studies indicating impaired development, and equally, there are many proclaiming no effect of depression on development. A study of 18-month-olds whose mothers suffered depressive symptoms while they were 6 weeks and/or 6 months old indicated that maternal depression had no effect on the<unk> 's cognitive development at 18 months. Furthermore, the study indicates that maternal depression combined with a poor home environment is more likely to have an effect on cognitive development. However, the authors conclude that it may be that short term depression has no effect, where as long term depression could cause more serious problems. A further longitudinal study spanning 7 years again indicate no effect of maternal depression on cognitive development as a whole, however it found a gender difference in that boys are more susceptible to cognitive developmental issues when their mothers suffer depression. This thread is continued in a study of<unk> ren up to 2 years old. The study reveals a significant difference on cognitive development between genders, with girls having a higher score, however this pattern is found regardless of the<unk> 's mother's history of depression. Infants with chronically depressed mothers showed significantly lower scores on the motor and mental scales within the Bayley Scales of Infant Development, contrasting with many older studies. A similar effect has been found at 11 years: male<unk> ren of depressed mothers score an average of 19.4 points lower on an Intelligence Quotient IQ test than those with healthy mothers, although this difference is much lower in girls. 3 month olds with depressed mothers show significantly lower scores on the Griffiths Mental Development Scale, which covers a range of developmental areas including cognitive, motor and social development. It has been suggested that interactions between depressed mothers and their<unk> ren may affect social and cognitive abilities in later life. Maternal depression has been shown to influence the mothers' interaction with her<unk> . When communicating with their<unk> , depressed mothers fail to make changes to their vocal behaviour, and tend use unstructured vocal behaviours. Furthermore, when infants interact with depressed mothers they show signs of stress, such as increased pulse and raised cortisol levels, and make more use of avoidance behaviours, for example looking away, compared to those interacting with healthy mothers. The effect of mother-infant interaction at 2 months has been shown to affect the<unk> 's cognitive performance at 5 years. Recent studies have begun to identify that other forms of psychopathology that may or may not be co-morbidly occurring with maternal depression can independently influence infants' and toddlers' subsequent social-emotional development through effects on regulatory processes within the<unk> -parent attachment. Maternal interpersonal violence-related post-traumatic stress disorder (PTSD), for example, has been associated with subsequent dysregulation of emotion and aggression by ages 4–7 years. Maternal drug use Cocaine Research has provided conflicting evidence regarding the effect of maternal substance use during and after pregnancy on<unk> ren's development.<unk> ren exposed to cocaine weigh less than those not exposed at numerous ages ranging from 6 to 30 months. Furthermore, studies indicate that the head circumference of<unk> ren exposed to cocaine is lower than those unexposed. On the other hand, two more recent studies found no significant differences between those exposed to cocaine and those who were not in either measure. Maternal cocaine use may also affect the<unk> 's cognitive development, with exposed<unk> ren achieving lower scores on measures of psychomotor and mental development. However, again there is conflicting evidence, and a number of studies indicate no effect of maternal cocaine use on their<unk> 's cognitive development. Motor development can be impaired by maternal cocaine use. As is the case for cognitive and physical development, there are also studies showing no effect of cocaine use on motor development. Other The use of cocaine by pregnant women is not the only drug that can have a negative effect on the fetus. Tobacco, marijuana, and opiates are also the types of drugs that can affect an unborn<unk> 's cognitive and behavioral development. Smoking tobacco increases pregnancy complications including low birth rate, prematurity, placental abruption, and intrauterine death. It can also cause disturbed maternal-infant interaction; reduced IQ, ADHD, and it can especially cause tobacco use in the<unk> . Parental marijuana exposure may have long-term emotional and behavioral consequences. A ten-year-old<unk>  who had been exposed to the drug during pregnancy reported more depressive symptoms than fetuses unexposed. Some short-term effects include executive function impairment, reading difficulty, and delayed state regulation. An opiate drug, such as heroin, decreases birth weight, birth length, and head circumference when exposed to the fetus. Parental opiate exposure has greater conflicting impact than parental cocaine exposure on the infant's Central Nervous System and autonomic nervous system. There are also some negative consequences on a<unk>  that you wouldn't think of with opiates, such as: less rhythmic swallowing, strabismus, and feelings of rejection. Malnutrition and Undernutrition Poor nutrition early in life contributes to stunting, and by the age of two or three can be associated with cognitive deficits, poor school achievement, and poor social relationships later in life Malnutrition is a large problem in developing nations, and has an important effect on young<unk> ren's weight and height.<unk> ren suffering malnutrition in Colombia weighed less than those living in upper class conditions at the age of 36 months (11.88 kg compared to 14 kg), similarly, malnourished<unk> ren were shorter than well-nourished<unk> ren, again at 36 months (85.3 cm in malnourished<unk> ren; 94 cm in well-nourished<unk> ren Malnutrition during the first 1000 days of a<unk> 's life can cause irreversible physical and mental stunting. Infections and parasites related to poor sanitation and hygiene can impact absorption of nutrients in the gut. Adequate sanitation and hygiene (rather than just access to food) play a critical role in preventing undernutrition, malnutrition and stunting and ensuring normal early<unk> hood development. Malnutrition has been indicated as a negative influence on<unk> hood Intelligence Quotient IQ. Although it is now suggested that this effect is nullified when parental IQ is considered, implying that this difference is genetic. Nutrients The effect of low iron levels on cognitive development and IQ is a subject still to reach consensus. Some evidence suggests that well-nourished<unk> ren with lower levels of iron and folate (although not at such a level to be considered deficient) have a lower IQ than those with higher levels of iron and folate. Furthermore, anaemic<unk> ren perform worse on cognitive measures than non-anaemic<unk> ren. These nutrients have been strongly implicated in brain development, along with iodine and zinc. Iodine is required for the generation of thyroid hormones necessary for brain development. Iodine deficiency may reduce IQ by an average of 13.5 points compared to healthy individual. Zinc deficiency has also been shown to slow<unk> hood growth and development. Zinc supplementation appears to be beneficial for growth in infants under six months old. Socioeconomic status Socioeconomic status is measured primarily based on the factors of income, educational attainment and occupation. Current investigations into the role of socioeconomic factors on<unk>  repeatedly show that continual poverty is more harmful on Intelligence Quotient IQ, and cognitive abilities than short-lived poverty.<unk> ren in families who experience persistent financial hardships and poverty have significantly impaired cognitive abilities compared to those in families who do not face this issue. Low income poverty can cause a number of further issues shown to effect<unk> , such as poor academic success, less family involvement, iron deficiency, infections, a lack of stimulation, malnutrition and lead poisoning due to lead paint found on the walls of some houses.<unk>  blood levels of lead increase as income decreases. Income poverty is associated with a 6–13 point reduction in IQ for those earning half of the poverty threshold compared to those earning twice the poverty threshold. That being said,<unk> ren coming from households featuring continual or temporary poverty still perform lower than<unk> ren in middle-class families. Parental educational attainment is the most significant socioeconomic factor in predicting the<unk> 's cognitive abilities, those with a mother with high IQ are likely to have higher IQs themselves. Similarly, maternal occupation is associated with better cognitive achievement. Those whose mothers' job entails problem-solving are more likely to be given stimulating tasks and games, and are likely to achieve more advanced verbal competency. Mother's employment is associated with slightly lower test scores, regardless of socioeconomic status. However, those whose working mother is of a higher socioeconomic status experience more disadvantages because they are being removed from a more enriching environment than a<unk>  care. Obviously, the quality of<unk>  care is a factor to be considered. Low income<unk> ren tend to be cared for by grandparents or extended family and therefore
Child development
Social emotional development
Motor skill
Child sexuality
Mental environment
Hearing
Sleep and metabolism
Maternal health