- If we took the DNA that is in a single cell – including that of the zygote – and laid it end-to-end, it would measure 1 metre. In fact, if we uncoiled all of the DNA within an adult human being, it would reach to the Sun and back … 340 times.
- Only one week after fertilisation, the embryo signals to the mother that she is pregnant by manufacturing and releasing its own hormone (human chorionic gonadotropin, or hCG). When the ovaries receive the hCG signal, they then continue producing progesterone, which maintains the lining of the uterus so that the embryo can implant there.
- The heart begins beating at 3 weeks and 1 day after fertilisation … and it will beat 54 million times before the baby is born. By 6.5 weeks, the heart has four chambers and is largely complete, beating more than 160 times per minute. At 7.5 weeks, electrical activity of the heart has a wave pattern similar to an adult’s.
- By 3 weeks the brain is already dividing into three distinct sections: the forebrain, the midbrain, and the hindbrain. By the fourth and fifth weeks, the brain further divides into a total of five different sections, and primitive brain waves have been recorded as early as 6 weeks and 2 days after fertilisation.
- At 6 weeks, the embryo begins to make reflexive movements. In fact, just before the seventh week, a touch to the mouth area will cause the unborn child to reflexively withdraw their head. By 8 weeks, the baby will grasp, move their jaw, squint, or point their toes in response to touch; in the low-gravity environment of the amniotic sac, the baby is even able to roll over – an ability that newborns can take up to five months to accomplish in the normal gravity outside the womb.
- Hiccups have been observed as early as 7 weeks; from 8 weeks, the fetus displays intermittent breathing motions. At 9 weeks, the baby can sigh and will have started sucking their thumb.
- Three-quarters of all babies at 8 weeks gestation exhibit right-hand dominance. The remaining quarter are equally divided into left-hand dominance and no preference.
- In female babies, the ovaries are identifiable by 7 weeks, and the uterus by 9 weeks. External genitalia also starts to take shape to the extent that a boy or girl can be identified visually.
- Between the 9th and 10th week, the baby goes through a burst of growth whereby its body weight increases by 75%!
- In the 11th week, the fetus’ intestines start to absorb glucose and water which has been swallowed; bowel movements, however, began far earlier – at 6 weeks.
Those are 10 astounding facts about the development of the unborn baby – but here is an extra fact as well:
- All of the above has happened just within the first trimester i.e. the first 3 months!
Source: The Endowment for Human Development, ‘Movie Theater’ http://www.ehd.org/movies-index.php