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.
* You can start to hear the babies heartbeat through ultrasound as soon as 6 weeks into your pregnancy! A Doppler can start to pick up a heartbeat at around 10-14 weeks into your pregnancy. A stethoscope can be used to hear the baby's heartbeat late in the pregnancy.