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.
When will I be able to hear my baby's heartbeat? At around 10 weeks, a Doppler ultrasound will allow you to hear your baby's heartbeat for the first timeâbut her heartbeat will already be visible on ultrasound by the time you are about six weeks pregnant. (To see what your baby's heartbeat looks like at six weeks, check out Drs. Doubilet and Benson's site: yourdevelopingbaby.com.) The first detection of the baby's heartbeat has both medical and emotional significance, says Dr. Doubilet.