Whats driving the twin pregnancy trend?
Many women are delaying pregnancy well into their 30s and beyond — when age-related hormonal changes may cause more than one egg to be released at a time. This boosts the odds of conceiving nonidentical (fraternal) twins. Because of their decreased fertility, older women are also more likely to use assisted reproductive technologies — such as in vitro fertilization — to conceive. Since these procedures typically involve implanting more than one fertilized egg in the uterus, they’re more likely to result in twins or other multiples. How multiples are made Fraternal twins — the most common kind — occur when two separate eggs are fertilized by two different sperm. Each twin has his or her own placenta and amniotic sac. The twins can be two girls, two boys, or a boy and a girl. Genetically, they’re no more alike than any other siblings. Identical twins occur when a single fertilized egg splits and develops into two fetuses. Identical twins may share a placenta, but each baby usually has a
