New Baby, Older Mom

Older pregnant women over age 45 are at higher risk for poor pregnancy outcomes

(RxWiki News) Having a baby as you approach middle age can be an unexpected surprise or a long hoped-for blessing. But there are risks to having babies as women grow older.

A recent study looked at the pregnancy complications associated with women aged 45 and older as compared to women in their 30s.

The researchers found that the older women were at higher risk for several negative pregnancy outcomes, such as preemies, gestational diabetes and low birth weight.

However, the study did not take into account women's weight or smoking status, which could have influenced the calculations of the risks.

"Talk to an OB/GYN about your own pregnancy risks."

The study, led by Mary C. Carolan, of the School of Nursing and Midwifery at Victoria University in Australia, looked at the rates of pregnancy complications among older pregnant women.

The researchers compared the pregnancy outcomes among 217 women aged 45 and older to those of 48,909 women aged 30 to 34. The researchers only included women who gave birth or had another outcome at 20 weeks of pregnancy or later.

The researchers found that women aged 45 and older were at a higher risk for a range of different pregnancy complications than the younger women.

Older women were about twice as likely to develop gestational diabetes than the younger women and almost twice as likely (89 percent more likely) to have a postpartum hemorrhage. A postpartum hemorrhage refers to excessive bleeding after a birth.

Older women were also nearly five times more likely to have placenta previa, where the placenta partly or completely covers the opening to the woman's cervix. The cervix is the route out for the baby, and this condition can cause severe bleeding before or during the delivery.

Women aged 45 and older were also a little more than two and a half times more likely than the younger women to have a preemie, born between 32 and 36 weeks of pregnancy.

If it was the woman's first baby, the risk of a preterm birth was three times higher than that of younger women. For later children, the risk was twice as high for older women than for younger women.

Older women were just over twice as likely to have a baby with a low birth weight (under 5.5 pounds) than younger women, though this risk was nearly four times higher if it was the woman's first child.

Older women were also about 53 percent more likely to have a baby who was underweight for the pregnancy week when the baby was born.

The highest risk associated with being an older pregnant woman was having a cesarean section. Women aged 45 and older who already had had children were just over eight times more likely to have a C-section than younger women who had already had kids.

Women aged 45 and older who used assisted reproduction, such as fertility treatments or in vitro technology, were almost six times more likely to have a C-section than younger women.

One weakness of this study is that there were far fewer older pregnant women to compare with the younger women. The fewer women who are available to compare, the harder it is to accurately estimate risk.

Another significant weakness is that the researchers did not have access to data on the women's income, educational level or weight and whether they smoked. All three of these factors – especially weight and smoking – influence birth outcomes, but these risk assessments could not take those factors into account.

The study was published March 27 in the journal BMC Pregnancy and Childbirth. The research received support from the Department of Health in Victoria and the The Consultative Council on Obstetric and Paediatric Mortality and Morbidity. The authors declared no conflicts of interest.

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Review Date: 
March 29, 2013