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 does the heart start beating in a fetus? 22 Days. 23 days after conception according to my Anatomy and Physiology Honors professor who is also an Ob/Gyn, in a closed circulatory system. However, you will not be ablâ¦e to hear the fetus' heartbeat until approximately 6 weeks, the latter part of the first trimester.