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.
What does my baby's heartbeat sound like? Many women say that the beating of their baby's tiny heart sounds like the thunder of galloping horses. Hearing it for the first time can be very moving. The heart rate of a healthy baby in the womb ranges from about 120 to 160 beats per minute. A heartbeat that's much faster or slower than that may signal heart problem. Inside pregnancy: Weeks 1 to 9