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.
8 out of 8 found this helpful. Cardiac activity in a developing fetus usually starts at the end of the 5th week. So by 6 weeks you should be able to see a heartbeat via ultrasound and by 10-12 weeks you should be able to hear the heartbeat via doppler device. A heartbeat would not be visible at 4-5 weeks of pregnancy. posted 10/26/2010 by sugar&spiceX3.