Antiretroviral timing in pregnancy is tricky.(Obstetrics)

SAN FRANCISCO -- The optimal time to initiate antiretroviral therapy during pregnancy depends on a balance of factors, Dr. Deborah Cohan said at a meeting on HIV management sponsored by the University of California, San Francisco.

The primary goal is viral suppression by the third trimester to minimize the chances of HIV transmission to the fetus. At least one study shows that the median time to viral suppression is about 50 days in pregnant women, although 10% fail to achieve total suppression within 6.5 months.

"In the United States we tend to start antiretrovirals between 12 and 14 weeks or beyond," said Dr. Cohan of the University of California, San Francisco. Many women "feel pretty bad in the first trimester, and the last thing we want is for them to ... attribute their nausea and vomiting to the antiretrovirals."

Women who have morning sickness may vomit up some of their medication, and that can create worries about whether and how to re-dose. Fortunately, the weight of the evidence is that transmission does not occur in the first trimester, so antiretroviral therapy may not be crucial during that time.

There are some situations, however, in which antiretroviral therapy would be appropriate during the first trimester. For example, if the woman is continuing her preconception regimen, and the regimen includes only nonteratogenic medications that are well tolerated, it need not be discontinued.

First-trimester antiretrovirals also are indicated in patients who need them immediately for their own health.

For women who fall to tolerate their preconception regimen during the first trimester despite the use of antiemetics, the recommendation is to discontinue all medications at once. The one exception is if the patient is on a regimen containing nonnucleoside reverse transcription inhibitors. In that case, discontinuation should be staggered.