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.
Sounds in the Womb. A baby can begin to hear sounds at about 17 weeks gestation, typically around the point when the mother begins to feel the first tiny flutters of movement and before the baby's sex is clearly identifiable. By 26 weeks, the baby's heartbeat will speed up in response to sounds, including music, that come from outside the womb. At 33 weeks gestation, babies have been observed breathing in time to music, indicating an awareness of the beat.