Pregnancy rate among HIV-positive women in the UK has increased significantly

Michael Carter
Published: 03 July 2012

The pregnancy rate among HIV-positive women in the UK increased significantly between 2000 and 2009, investigators report in the online edition of AIDS. There were rises in incidence of first and repeat pregnancies. Younger age, a higher CD4 cell count and ethnicity were all predictors of pregnancy.

“All HIV-positive women who are pregnant or planning a pregnancy require a high level of clinical care,” emphasise the authors. “Demand for services is likely to increase further, particularly as an increasing number of older women have pregnancies. Older women, particularly those over 40, are at increased risk of experiencing fertility problems and pregnancy complications, some of which are also associated with antenatal ART [antiretroviral therapy] use.”

Becoming pregnant and having an HIV-negative baby are now realistic options for the majority of HIV-positive women of childbearing age in the UK. With the right treatment and care, the risk of mother-to-child transmission of HIV can be reduced to below 1%, and developments in treatment and care have lead to improvements in health, fertility and life expectancy.

Little is currently known about the incidence of pregnancy among HIV-infected women in the UK. The characteristics of women who become pregnant are also poorly understood. Nevertheless, it is important to understand these issues given the high level of specialist care that HIV-positive women require during pregnancy.

A team of investigators therefore analysed data collected from two studies, the UK Collaborative HIV Cohort (UK CHIC) and the National Survey of HIV in Pregnancy and Childhood. A total of 7853 women aged between 16 and 49 who received care between 2000 and 2009 were included in the present study. The number of women receiving care doubled over the course of the study.

There were 1637 pregnancies among 1291 women. Most women (78%) had a single pregnancy, but 19% had two and 4% had three or more. The number of pregnancies increased threefold over the course of the study, from 156 in 2000-01 to 450 in 2008-09.

The proportion of pregnancies among women aged between 36 and 49 increased from 37% at the beginning of the study to 58% by its end. The percentage of repeat pregnancies also rose from 30% in 2000-01 to 52% in 2008-09. This increase was highly significant (p < 0.001) and was seen in all age groups.

In 200-/01, only 46% of women were taking antiretroviral therapy, but this had increased to 64% by the end of the study. The rise in the proportion of people taking treatment was reflected by a steady increase median CD4 cell count, from 338 cells/mm3 to 458 cells/mm3.

Rates of pregnancy increased in women of black African or black Caribbean ethnicity, but fell in women of white ethnicity (p < 0.001).

Almost all the pregnancies involved women infected with HIV via heterosexual sex (97%).

Incidence of pregnancy increased from 3.4% in 2000-01 to 4.5% in 2008-09. The likelihood of a women becoming pregnant increased as the study progressed (RR  per later year = 1.05; 95% CI, 1.03-1.07; p < 0.001).

Predictors of pregnancy included younger age (p < 0.001) and higher CD4 cell count (above vs below 350 cells/mm3, p < 0.001). Women of white ethnicity were significantly less likely to become pregnant than those of black African or black Caribbean ethnicity (p < 0.001).

In the first set of analyses, women who were taking HIV therapy were less likely to become pregnant, but this ceased to be the case after the investigators had controlled for confounding factors.

Overall, 1421 pregnancies (87%) resulted in a delivery, and almost all of these (1401) were live births. There were 126 miscarriages, 63 terminations and four ectopic pregnancies. The proportion of pregnancies resulting in delivery increased over time (p = 0.05) and the proportion resulting in termination decreased from 13% at the start of the study to 3% in 2008/9 (p < 0.001). The investigators believe this is likely to be because the risk of mother-to-child transmission decreased over the course of the study. Improved prognosis may also have been a factor.

“HIV-positive women with or planning a pregnancy require a high level of clinical care and this is likely to continue particularly as more older women have pregnancies,” conclude the authors.

Reference

Huntington SE et al. Predictors of pregnancy and changes in pregnancy incidence among HIV-positive women accessing HIV clinical care at 13 large UK clinics. AIDS, online edition. DOI: 10.1097/QAD.0b013e3283565df1, 2012.