Pregnancy and the Development of the Child |
First Trimester
(Weeks 1 - 12) |
| Weeks 4 - 10 | The period with the greatest risk of birth defects. |
| Week 4 Day 1 | The baby's fetal organs begin forming. |
| Weeks 4 - 6 | The baby is a small, almost tadpole-like embryo. During this time, vital organs develop, which will include the spine, heart, digestive tract, and arm and leg buds. |
| Weeks 6 - 10 | The baby will weigh approximately one third of an ounce and grow to about one and one fourth inches. The heart will be beating and the arms and legs will grow and begin developing fingers and toes. |
| Week 9 Day 1 | Major organs have already formed. |
| Weeks 8 - 12 | The baby will be about two and a half to three inches long and weigh about a half ounce. Amniotic fluid cushions the fetus, allowing the baby to move easily. A baby is able to open and shut its mouth and turn its head, as well as make a fist and kick. More organs are beginning to develop, including the reproductive organs. It is, however, difficult to determine the gender at this point. |
Second Trimester
(Weeks 13 - 27) |
| After Week 12 | The risk of miscarriage decreases sometime after week 12. |
| Weeks 16 - 20 | The baby now weighs between four and six ounces and is four to five inches long, with the head making up about one-third of its length. The baby will grow very rapidly during weeks 16-20 and the baby’s gender can probably be determined by this point. The eyelashes and fingernails have begun to grow, but the toenails have not. And, even thought the vocal chords have formed, the baby is unable to cry.
The baby’s nourishment is being provided by the placenta. The baby has begun swallowing amniotic fluid and is now urinating and forming meconium, the stool, in its intestines. The tongue is also working, so the baby can begin gentle sucking. |
| Weeks 20 - 24 | The baby will weigh between eight ounces and a pound and is eight to 12 inches long, still small enough to hold in the palm of your hand. The head, body, arms and legs are proportionate in size. Toenails, eyebrows and hair are beginning to grow and teeth are forming under the gums. There is a fine, soft hair now covering the body called lanugo, and a creamy, white covering all over the skin called vernix. During this time the mother will begin feeling the baby move, but she could mistake it for gas bubbles. The baby is able to kick and turn over by now, and everyday maternal activity gently rocks the baby in the amniotic sack. |
| After Week 22 | If the baby is premature, but born sometime after week 22, he/she has a chance to survive with intensive care. |
| Weeks 24 - 28 | The baby weighs about one and one half pounds and is between 12 and 14 inches long. There is little body fat and the skin is still very thin. The eyelids are beginning to part and your baby can open its eyes. Because it is swallowing some amniotic fluid, the mother can feel rhythmic jerks or jolts when it hiccups. A baby’s unique fingers and toes are now visible. During these weeks the mother may begin to recognize the baby’s pattern of activity and rest. It is different for every baby, but most will kick or turn at least 10 times in a 12-hour period. |
Third Trimester
(Weeks 28 - 40) |
| Weeks 28 - 40 | During the third trimester, a baby will grow significantly. In fact, it will more than double its weight. |
| Weeks 28 - 32 | At this point, the soon-to-be newborn only weighs two to three pounds and is 14 to 17 inches long. Lanugo, the fine downy hair, begins to disappear, first from the face, while the vernix, the thick creamy-white substance, still protects the skin. The baby’s vision has developed and his/her ears are now capable of picking up sound. If a light is shone directly on the mother's abdomen, the baby will react to it. The baby can also hear the mother's heartbeat, as well as food moving through her body and blood flowing through her uterus. The baby also knows her voice and enjoys certain kinds of music. Loud music or sudden movements will cause the baby to jerk, a startle reflex. A baby’s movements over the next several weeks become more intense. |
| Weeks 32 - 36 | By sometime around week 32, the baby weighs approximately five pounds and is from 16 to 18 inches long. This is a time for tremendous growth, especially of the brain. Most of the baby’s systems are well developed by this point, except the lungs, which could still be underdeveloped. Calcium, protein and iron are very important in these last few weeks of growth. The baby is developing skills that will allow it to eat, and taste buds are now present on his/her tongue. |
| Weeks 36 - 40 | The baby is now plump and pink, smooth skin and can weigh from six to nine pounds, waiting for its debut to the world. |
| Week 40 | The baby should be born at week 40. |
