There are a few medical reasons to stop breastfeeding during pregnancy, but on the whole, there is no reason to stop if the pregnancy is not problematic. As long as the mother is eating a balanced diet, drinking plenty of fluids and resting, the body will be able to cope with any extra demand upon its resources. Stimulation of the nipple can release a hormone called oxytocin into the body, which may then cause uterine contractions or cramping, but this should only occur after the 37th week of pregnancy.
Women who are going through a healthy pregnancy have little to worry about in terms of breastfeeding during pregnancy. It is very important that the mother stays well hydrated, as dehydration can become an issue while breastfeeding and this is dangerous for the developing baby. Another source of concern is that breastfeeding can cause a calcium deficiency. This is not a problem for the baby, as the baby gets what it needs before the mother does, but it may be an issue for the mother.
Breastfeeding during pregnancy can be problematic if there is a history of premature labor or miscarriage, or if there is bleeding. In these cases, it may be better to wean a first child while pregnant with a second. In any case, it is advisable to seek medical advice, but there is not always a consensus in medical circles. For this reason, two or three opinions may be a good idea.
During the fourth and fifth month of pregnancy, there is a change in the breast milk to a pre-milk called colostrum, which is necessary for a newborn. The baby or toddler who is being breastfed will notice the change in taste and may or may not accept it. In the former case, this is not a problem, as the mother's body will continue to produce colostrum until the new baby is born. A check on the breastfeeding child's weight should be done in order to ensure that he or she is putting on enough.
Tandem breastfeeding is when both the newborn and the older child are breastfed either concurrently or at different times. This is thought to create a special bond between the siblings that may stave off jealousy. Some mothers find that if they continue breastfeeding during pregnancy, feeding the newborn is easier, as there are fewer problems such as nipple trauma.