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Is it necessary to ...

  1. Use a condom during intercourse during the last month or two of pregnancy, to prevent infection?
  2. Undergo a CVS test or amniocentesis while pregnant, if I'm over 35?
  3. Stay off birth control pills while breastfeeding?


No, this is not necessary.


Genetic testing is routinely offered to women who will be older than 35 years at time of delivery because the risk of Down's Syndrome and other chromosomal problems increase with maternal age. Either Chorionic Villus Sampling (CVS) or amniocentesis can detect the baby's sex, the number of chromosomes and any large defects in the chromosomes. The difference in the two methods comes down to when they are done and the risk.

CVS is performed between 10 and 12 weeks of pregnancy and involves taking a sample of the placenta for analysis. Since it is performed earlier in the pregnancy, results are available sooner, but the risk of miscarriage from the procedure is approximately 1%. There has been some controversy over whether CVS causes defects in the fetus's limbs, but those cases are seen if CVS is performed at less than 10 weeks of pregnancy.

Amniocentesis can be performed anytime after 14 weeks and has a procedure-related miscarriage rate of 1 in 250-300. The procedure involves taking about 2 tablespoons of amniotic fluid, which is composed of fetal cells and fetal urine, with an ultrasound guided needle. The fluid is typically analyzed for either chromosomes or for fetal lung maturity. Amniotic fluid will sometimes leak after an amniocentesis, but we believe that it does not occur after each procedure because the hole is small and the hole can "re-seal." Since the procedure is performed later in pregnancy, the results come later.

There is no right or wrong answer of which procedure, if any, is best for you. The majority of women opt for amniocentesis, given the lower complication rate.

Stay off birth control pills while breastfeeding?


Hormonal contraception that does not contain estrogen (the minipill, Depo Provera, etc.) is not felt to decrease milk production.

For more information:

Go to the Pregnancy health topic, where you can:

Last Reviewed: May 28, 2002

Arthur T Ollendorff, MD Arthur T Ollendorff, MD
Associate Professor of Obstetrics and Gynecology
College of Medicine
University of Cincinnati