The Hidden Realm
No relationship can be closer than that of a mother and her unborn child—yet the miraculous process taking place inside of you may seem as much of a mystery to you as to anyone else. A grainy black-and-white ultrasound image can be inspiring and reassuring, but it doesn’t show you very much about your baby.
What does this developing life really look like at 6 days after conception, at 6 weeks, at 6 months? How do intricately complex organs like the eyes form? When does your baby first suck his or her thumb—inside the womb? What does the embryonic heart look like when it starts beating, only about 21 days after conception? How much does your baby’s brain grow in the space of a month?
The moment a sperm penetrates the egg, chemical messengers relay news of the event to the brain, and the mother’s body immediately prepares for the new life. Tubal muscle movements and tiny hairlike projections called cilia transport the fertilized egg through the tube and into the uterus. The microscopic fertilized egg bores into the lush lining of womb, secures its site, and commences to grow with a vengeance.
Early Days
Whether they will become flatworms, lizards, or humans, embryos all develop in much the same way. The human embryo at about a month, when it is no bigger than a grain of rice, appears to be a tiny reptile, complete with tail.
Changes take place with amazing rapidity. About 21 days after conception the tiny, rudimentary heart begins to beat. At around 2 months, the embryo begins to acquire a clearly human aspect. The tail shrinks and toes and fingers become distinct. Inside the embryo, nerves feather themselves throughout the body and sex organs start to develop.
The months of pregnancy progress and the beauty and logic of the unfolding of life become clear. As though in a long, slow dance, eyes travel toward the front of the face while ears gradually climb up the head. Buds become limbs, toes and fingers emerge, facial features form—the fetus kicks, sucks his thumb, smiles.
After 9 months, this portion of your baby’s fantastic journey is complete. Everything lies in readiness for life outside of your protective womb—and the next stage of the journey.
Welcome to Your Baby’s World
The fertilized egg, termed a zygote, divides into 2 cells after about 24 hours, 4 cells after 48 hours, and 6-12 cells in 3 days. At about 5 days, the zygote has transformed into a hollow ball called the blastocyst.
The heart develops by folding in upon itself like a piece of origami. The early heart is not much more than two simple tubes that have fused together, twisted, and looped back on themselves. By week 5, the twisted tube fuses and becomes a two-chambered heart with one atrium and one ventricle. By week 6, a vertical wall known as the septum grows up into the middle of the two chambers.
By the time the baby is born, the brain will contain about 100 billion neurons—almost all the neurons it will ever have. The ear begins its development in the neck area and migrates up to the side of the head.
The embryo floats in an interior ocean—the amniotic fluid—contained by a membrane called the amnion. Salt is dissolved in the amniotic fluid in the same proportions as it is in our blood, tears, and the Earth’s oceans.
A woman's body undergoes enormous changes during pregnancy. The heart and kidneys must work harder because blood volume is higher. Cardiac output increases 30-50%. Heart rate increases to 80-90 beats per minute. The enlarged uterus, which reaches the lower edge of the rib cage by 36 weeks, compresses the bladder and intestines. This makes it necessary to urinate frequently, and it may also cause constipation. The mother’s spine curves more to balance the weight of the growing uterus.