What are the risks for the mothers? Compared with women under the age of 35, those giving birth at 35
and over are more likely to have pre-existing hypertension and to develop hypertension and pre-eclampsia, a
serious pregnancy condition in which high blood pressure and protein in the urine develop after the 20th week
of pregnancy. They are also more likely to develop diabetes during their pregnancy, to experience placenta
previaa complication in which the placenta is located low in the uterus and may block the cervix, and to
have a Caesarean delivery. The literature on placental abruption, a complication in which the placenta
prematurely separates from the uterus, is mixed; some researchers found that only women age 40 and over
were at an increased risk compared with women under 35.7 Other studies have found that women between
35 and 39, but not those 40 and over, were at an increased risk when compared with women between ages
20 and 24.
What are the risks for the babies? Studies that have looked at the link between adverse birth outcomes
and mothers age have shown that women 35 and over face an increased risk of delivering preterm (less
than 37 weeks), low birth weight or small-for-gestational-age babies. A recent Canadian study found that
first-time mothers age 35 and over were at increased risk of preterm births. Others have reported that babies
born to those at an advanced age are at increased risk of non-chromosomal abnormality, chromosomal
abnormality and congenital anomaly. One study argues that the widespread screening for fetal defects in
pregnant women age 35 and over has resulted in fewer live births of infants with congenital anomalies.