The alien look of an early fetus on ultrasound is disappearing as the eyes move closer together and the ears shift into their normal location. The baby’s sex could be viewed if an ultrasound could see that far into the womb, but parents will need to wait until at least the 16th week to find out. Intestines that developed in the umbilical cord continue to move into baby’s body, and liver and pancreas function begin.
The 13th week is the first week of the second trimester. Many pregnant women wait this long to assure the pregnancy is not going to have any complications before telling friends, family, and co-workers about being pregnant. Most women agree the second trimester is the time when the body feels great and the tummy is not quite big enough to get in the way.
As the uterus grows larger, ligaments in the abdomen may stretch causing a bit of pain. Some expecting women, especially those carrying their first pregnancy, could confuse these pains with contractions. If pain exists, go to your primary caregiver.
The 13th week is pretty dull medically. The fetus is growing and the body is changing, but that happens throughout the 40 weeks.
The second trimester is a great time for an expecting father. Mom may be feeling good enough to resume an active sex life, which is completely safe during pregnancy. Exercise, dancing and general fun is all part of trimester two.
The body is doing great things right now so fatigue may still pop up from time to time. Fatigue can also be caused by eating too few calories. As activity levels increase – the pregnant woman is feeling better – calorie intake needs to rise as well. And when you're tired, sleep.