pregnancy fetus week 12

Your Baby

The 12th week starts a new day for the fetus. Growth speed is increasing exponentially and formed organs are starting to practice the functions they will have outside of the womb. The intestines, for instance, start practicing peristalsis. Peristalsis is the muscle movement of the intestines that helps during digestion. Amniotic fluid builds up in the womb as the kidneys start to produce urine. Urine output is collected and consumed by the fetus to maintain healthy fluid levels.

Measurements @ 12 weeks

Average length of fetus : 2.1 inches (54 mm)
Average weight of fetus : 0.5 oz (11 gm)

Your Body

The uterus makes a move upward during week 12 of pregnancy. This relieves some of the pressure on the bladder that has caused those frequent trips to the bathroom for the first 11 weeks. Throughout the second trimester, the bladder will be relatively safe from uterine pressure but the pressure will return in the third trimester as the uterus grows larger than ever. Fatigue may be fading away, but headaches and feeling a bit dizzy is common as your body continues to increase blood volume to meet fetal needs.

While the genitals are forming during the 12th week, most often they are not visible on ultrasound until the 16th week of pregnancy. Ultrasounds are not required for a healthy pregnancy, but many doctors order them or perform them in office to gauge fetal growth and give expecting parents a chance to see the baby for the first time. The first-trimester screening test for chromosomal and other anomalies can be done until the end of the 12th pregnancy week.

At the Prenatal Visit

Between 11 and 14 weeks of the pregnancy, a test called "nuchal screen" or nuchal translucency test is often done to screen for Down syndrome. You can check your risk for having a baby with Down syndrome here. The "First Trimester Screen" or "Nuchal Translucency Screen" is done to assess risks of Down syndrome but it also is used to identify other chromosomal anomalies.


As early symptoms are fading away, expectant women tend to feel like their old selves again for a while. Dad can help out by exercising regularly and asking Mom to come along. Exercise is beneficial throughout pregnancy to keep the body strong and prepare Mom for the challenges of childbirth.

Tips For This Week

Just because exercise is a great choice while pregnant does not mean advanced aerobics or heavy lifting is an approved activity. It is important to discuss exercise with your doctor before going out and training for a triathlon.

Read More:
Pregnancy: Week by Week