Questions about pregnancy and fertility are best answered by an obstetrician/gynecologist (OB/GYN). OB/GYN specialists in reproductive endocrinology
and infertility or maternal-fetal medicine may also be consulted.
As women age, their ability to conceive decreases and their likelihood of having a child with certain kinds of birth defects increases. However, this does not mean that women in their 40's cannot have healthy babies.
The risk of genetic defects such as Down's syndrome in babies born to older women is a result of genetic changes that can occur in the unfertilized egg cells as a woman ages. There is no external way to predict whether a given pregnancy has resulted in a fetus with genetic abnormalities, but it is possible to sample amniotic fluid or even blood from the umbilical cord during a pregnancy and test for these abnormalities.
In addition, it is also possible for an older woman to undergo an assisted reproduction technique, such as in vitro fertilization, in which only healthy eggs are fertilized and then re-implanted. IVF can be very expensive and emotionally challenging for the woman or couple trying to become pregnant, but it has resulted in the births of thousands of healthy children in older women.
Overall, it is possible for women in their 40's to safely have a baby. Exploring the available options and discussing the pregnancy risks for an older woman involve very personal conversations that are best had with an obstetrician.