By pregnancy week 21, the infant’s growth is now slower down somewhat though the infant is still developing and under growth at a remarkable pace. It is during the pregnancy week 21 the infant's important bodily organs and central nervous system are still getting developed and matured. The infant's skin continues to develop and mature as well. Although not totally matured or developed, the infant's digestive system is also at work but minimum during 21st week of pregnancy.

The intestines are gradually starting to contract and relax during pregnancy week 21, and the infant is able to swallow and absorb fluids from the amniotic fluid at 21st week of pregnancy. Though it looks like unusual that the infant might swallow amniotic fluid, this in real, helps maturing the digestive system. At some point in the gestational period, the mother may actually start observing that her infant has started hiccupping. Whether anyone believes it or not, the hiccupping in uterus is certain and very common, and typically not a symptom that the infant is in distress.

Fetal hiccup ideally begins sometime during the 2nd trimester and the mother might notice hiccups as a small, repetitive and rhythmic motions that occur for a few minutes at a time in her abdomen. Many expecting mothers actually enjoy this type of sensation of their infant's hiccups since it makes them remember that all is well with her newborn infant. Some of the infants will hiccup more than others whereas one of the expecting mothers may only notice her baby hiccupping on some occasion; another may observe the infant hiccups more than five times a day.

While the mother is under growth during pregnancy week 21, the belly is still a size that is quite manageable. This also allows a superb deal of movements with freedom. Many expecting mothers enjoy the 2nd trimester and believe it the honeymoon of pregnancy. The mother also notice ache and pain in her leg during or after 21st week of pregnancy. Just as with varicose veins, those are quite common during previous weeks, support stockings may assist alleviating the leg heaviness and aches while in pregnancy week 21. One should also try to put the maternity support hose on 1st thing in the morning before she gets up from the bed. This helps alleviating unnecessary inflammation and discomfort in the lower extremities.

The expecting mother should also consider propping the feet up while sitting if she does not already doing so. Another technique for alleviating the aches and pains is regular exercising including stretching. She should consider a 15-minute stretching and walking during the lunch break or once in the morning and another during the afternoon. This goes a long way towards alleviating body ache and various body pains.