Trimester One – Weeks Seven through Twelve

The second half of the first trimester represents a crucial time in a fetus's development, and a light at the end of the tunnel for women experiencing difficult first-trimester pregnancy symptoms.  During this period, the fetus's limbs, organ systems, and sex organs are refined, and parents can look forward to finding out the fetus' sex.

First Trimester Fetus Growth and Development

Week Seven

The fetus's limbs and eyes and ear buds, and the umbilical cord linking the fetus to the placenta, are visible.

Week Eight

The fetus forms fingers and toes, and the facial features become more distinct.

Week Nine

During the ninth week, the fetus may begin moving.  Hair follicles and reproductive organs begin to form.

Week Ten

All the vital organs, fingers, and toes are in place.  The skeleton begins to form, and male fetuses begin producing testosterone.

Week Eleven

The fetus begins to grow more rapidly, nourished by the growing placenta.  Genitalia become discernable by the end of this week.

Week Twelve

Week twelve marks the end of the first trimester.  By this week, the fetus is nearly three inches long, and has developed finger and toe nails.

Early Pregnancy Symptoms

At the beginning of the second half of the first trimester, the uterus continues to grow, causing the woman's waistline to thicken a bit.  Weight gain is typically minimal at this point, since pregnancy hormones continue to cause nausea, constipation, food aversions and cravings, and other symptoms that tend to curb the appetite.  Mood swings, which are caused by hormonal fluctuations, are also common and normal.  As the placenta matures, it takes over production of some of these hormones, and symptoms diminish toward the end of the first trimester.

Continued Reading:

Trimester Two - The First Half