Pregnancy after age 35

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Pregnancy after age 35

Most women who are older than 35 have healthy pregnancies. But as you age beyond your mid-30s, some risks do increase. If you are an older mother-to-be, you can increase your chances of having a healthy pregnancy. See your doctor for a checkup before you become pregnant. Keep a regular schedule of prenatal checkups when you are pregnant.

Pregnancy risks vary from woman to woman. Some pregnancy problems, such as preeclampsia and gestational diabetes, are more common in older pregnant women. The greatest age-related risks over age 35 are of infertility and miscarriage. Birth defects linked to mother's age are much less common.

Most cases of Down syndrome pregnancies (and other chromosome problems) occur in older women. Fetuses with these birth defects are found in about:¹

• 1 in 200 women age 33.
• 1 in 130 women age 35.
• 1 in 40 women age 40.
• 1 in 12 women age 45.

Because the chances that your fetus will have a chromosome-related problem increase in your later 30s and 40s, your doctor or nurse-midwife will probably recommend a birth defects screening.

Birth defects screening and testing

Talk to your health professional about birth defects screening and testing options.

• Though it is not widely available, you may be able to consider a combination of first-trimester screening tests to look for possible Down syndrome. The screening combines ultrasound measurement of the thickness of the fetus's neck (nuchal fold) and measurements of beta-human chorionic gonadotropin (beta-hCG) and a protein called pregnancy-associated plasma protein A (PAPP-A). This screening is about as accurate as the second-trimester maternal serum quadruple screening.²
• Chorionic villus sampling (CVS) is a diagnostic test that can be used to detect Down syndrome and inherited diseases during the first trimester, rather than waiting until the second trimester for an amniocentesis. CVS is done between the 10th and 12th weeks of pregnancy. It does not detect neural tube defects (which are not related to age).
• An amniocentesis is a diagnostic test that can be used to detect birth defects. It is done to collect amniotic fluid. The fluid is tested for genetic problems. Amniocentesis is done between the 15th and 20th weeks of pregnancy, usually around week 16. Some medical centers offer "early" amniocentesis at about 12 to 14 weeks, but there are increased risks to your fetus with an early amniocentesis compared to a later amniocentesis.³

A recent study showed that both tests had a small risk of miscarriage. In that study with highly trained providers, the risk was about 1 in 400.⁴ Some studies have shown higher miscarriage risks, between 2 and 4 in 400.⁵ This greater risk may be more likely in centers with less experienced providers, especially for CVS. The CVS risk may be less when it is done through the abdomen than when it is done through the cervix.⁶

For more information, see the topic Birth Defects Testing.

References

Citations

1. Cunningham FG, et al. (2005). Prenatal diagnosis and fetal therapy. In Williams Obstetrics, 22nd ed., pp. 313–339. New York: McGraw-Hill.

2. American College of Obstetricians and Gynecologists (2004). ACOG issues position on first-trimester screening methods. Available online: http://www.acog.org/from_home/publications/press_releases/nr06-30-04.cfm.

3. Canadian Early and Mid-Trimester Amniocentesis Trial (CEMAT) Group (1998). Randomised trial to assess safety and fetal outcome of early and midtrimester amniocentesis. Lancet, 351: 242–247.

4. Caughey AB, et al. (2006). Chorionic villus sampling compared with amniocentesis and the difference in the rate of pregnancy loss. Obstetrics and Gynecology, 108(3): 612–616.

5. Seeds JW (2004). Diagnostic mid trimester amniocentesis: How safe? American Journal of Obstetrics and Gynecology, 191: 608–616.

6. Alfirevic Z, et al. (2006). Amniocentesis and chorionic villus sampling for prenatal diagnosis. Cochrane Database of Systematic Reviews (1). Oxford: Update Software.

Credits

Last updated:	November 30, 2006
Author:	Shannon Erstad, MBA/MPH
Reviewed By:	Renée M. Crichlow, MD - Family Medicine, Kirtly Jones, MD - Obstetrics and Gynecology
Editors:	Kathleen M. Ariss, MS, Pat Truman, MATC