months four-six

crown-rump length (CRL): from the head to the toe.

Fourth month

external image 4-month-fetus.jpg
by the weeks 13–14,the fetus has a CRL of about 3 inches (8 cm)and weights 140 g.The sex of the fetus can be seen,the mouth is formed.
and hair begins to grow.In male fetus the prostate gland begins developing and in female fetus ovaries move from the abdomen to the pelvis.
The legs and feet get well developed and his skin is transparent.

In weeks 15–16 the fetus has a CRL of about 4.5 inches (12 cm).Females develop hundreds of eggs in the ovaries.

Fifth month

external image 5.jpg
By weeks 17–18 the fetus has a CRL of 5.5–6 inches (14–15 cm), the fetuses musclegets stronger and the fetus becomes more energetic.
On weeks 19–20 the fetus has a CRL of about 6.5 inches (16 cm)and lanugo,(a fine hair) covers the body.In female fetus the uterus is completely formed.

Sixth month

external image fun_weird_amazing_crazy_offbeat_a+baby+in+the+making6_20090718114610595.jpg
In weeks 21–22:the fetus has a CRL of about 7 inches (18–19 cm).Bone marrow starts making blood cells and taste buds begin to form.

In weeks 23–24:the fetus has a CRL of about 8 inches (20 cm) and eyebrows and eyelashes usually develop.