The first meaning is 'metre' which is a measurement of length. If the 'm' stands alone it is metre. The second meaning is 'milliâ¦' which means a thousandth. In this case 'm' can not stand alone, we need to know what we have a thousandth of; if it is weight, length or some other thing. Example: mg means 'milligram', a thousandth of a gram. Example: mm means 'millimetre', a thousanth of a meter.
At about six weeks into pregnancy (four weeks from conception), you should be able to see your baby's heartbeat on ultrasound. The typical heart rate at this age is about 100 beats per minute.
In general, you will be able to hear your baby's heartbeat when you are about 8 weeks pregnant using an obstetrics ultrasound. Or you may be able to hear the baby's heartbeat during regular prenatal care visit at 10 weeks, or more commonly at 12 weeks, with a fetal Doppler. The new fetal care technologies now allow for a much more specific time frame. We now know that your baby's heart begins to beat around 6 weeks after conception.