Week 21 marks a slight slowing of the growth process. The fetus continues to grow, but more attention is paid to internal organs and development than weight gain. Length does not slow as rapidly, so the fetus may take on an extremely thin façade for a while. Male fetuses begin to drop the testes during week 21. The testes will move from inside the body into the scrotal sac. Heart growth and strength is the major focus.
Pregnant women with multiples may have some concerns about fetal battles in utero. Twin or triplet fetuses will kick and punch each other on a regular basis. The babies are separated with a thick, elastic wall that prevents harm. The walls of the amniotic sac are extremely strong, so neither baby will kick through to break the bag of waters in battle.
The uterus continues to grow – up. It has reached ½ inch above the navel. Pregnancy weight gain may have reached 10 to 15 pounds by this point in gestation and will continue to increase gradually. Eating a healthy, well balanced diet means mom does not have to coun calories as strictly as she normally would. The body needs extra calories for baby, but also for personal growth and changes that continue to occur throughout the 40 weeks.
Multiples tend to cause more swelling than singlets. Resting often and propping up the feet is crucial to making it through the next 17 weeks with two or more fetuses growing.
Expecting moms no longer feel like getting sick every few moments and some food and scent aversions may also be fading away. This is the ideal time for mom and dad to take some time for themselves. Traveling is allowed during pregnancy, but the attending doctor needs to be consulted before long trips or flights. Sitting for long periods of time can increase the risk of blood clots in the legs. The doctor may have some advice on how to prevent these clots from occurring. Multiple pregnancies are far more risky than singlet pregnancies so travel restrictions may start soon.
Eat well, drink well and live well. This is the brightest and most comfortable time in pregnancy so expecting women need to take advantage of these next few weeks of comfort.
There are no routine medical tests or appointments required during the 21st week. Most often, all testing (for now) is done so the pregnant couple can live life and enjoy the growing fetus.