A child's largest, fastest growth spurt is not during the first post-birth year or adolescence but over the course of pregnancy, especially during the first trimester, or first three months, well before women can detect fetal movements. Regardless olf whether you are currently pregnant, you are not alone if you are curious about the astonishing facts of prenatal development. Please note: Pregnancy length is calculated here from conception, not the date of the mother's last menstrual period.
First Month
With conception, an ovum (egg) cell fuses with a sperm cell in the fallopian tube, between the ovary and uterus. The rapidly growing new life form implants in the womb's lining and starts forming the placenta, its nourishment source throughout the pregnancy. By one-week post-conception, the heart, brain, spinal cord and gastrointestinal tract begin forming. By four weeks, the limbs, nose, jaw, palate and lungs are taking shape, and the heart is beating.
Second Month
The accelerating development of brain, spinal cord and limbs give rise to the first movements an ultrasound can detect. By week five, the embryo has begun to form all the organs present in an adult's body. The hair and nipple follicles, closed eyelids, ears, tongue, bones and genitals emerge. The face grows ever more recognizably human.
Third Month
The head takes up nearly half of the fetus' body. The hands and arms develop faster than the feet and legs. Nails and baby teeth buds appear. By the end of the third month and first trimester, the fetus--originally a single cell created through the fusion of sperm and egg--has grown to 3.5 inches long and weighs a little more than an ounce. The baby can make a fist, suck its thumb, suck and swallow the amniotic (surrounding) fluid, stretch, grasp and yawn.
Second Trimester (Fourth Through Sixth Months)
All organs continue to mature. Egg cells appear in a girl baby's ovaries, and a boy baby's testicles descend. Toe prints and fingerprints become visible. The baby starts hearing and goes through a regular sleep-wake cycle. Most women begin to feel their babies' already active movements around 18 weeks. The earliest-known surviving premature babies were born during this trimester, at around 21 weeks. Preemie survival rates increase dramatically between the 23rd and 25th weeks.
Third Trimester (Seventh Through Nine Months)
The previously closed eyes open and respond to light. Taste buds and the ability to distinguish sour and sweet emerge, along with hiccuping. The fetus rapidly puts on weight, develops mature lungs and positions itself upside-down. The skeleton hardens except for the skull. From one cell at conception to 3.5 inches long and an ounce in weight at three months, the baby grows to about 20 inches long and 6 to 9 pounds by full-term birth.
References
- American College of Obstetricians and Gynecologists: How Your Baby Grows During Pregnancy
- American Pregnancy Association: Fetal Development
- Quint Boenker Preemie Survival Foundation: Premature Birth Statistics
- Toronto Hospital for Sick Kids: AboutKidsHealth.ca: Fetal Development
- Zero to Three: Frequently Asked Questions
