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.
At about 5 weeks gestation, your baby's heart begins to beat. 1  At this point, a normal fetal heart rate is about the same heart rate as the mother's: about 80-85 beats per minute (BPM). 2  At this point, it begins a rapid deceleration to the normal fetal heart rate for the middle of the pregnancy to about 120-180 BPM.