No increase in adverse birth outcomes with IPT-exposure in pregnancy in two African cohorts

Izoniazid preventative therapy (IPT) did not increase the risk of adverse birth outcomes among pregnant women with HIV in analyses from South Africa and Kenya, presented at the Union 51st World Conference on Lung Health 20–24 October 2020. [1, 2]

There was a greater number of live births and fewer miscarriages among the South African women who received IPT than those who did not. And no difference in risk of preterm delivery and other adverse birth outcomes between the Kenyan women starting and not starting IPT in pregnancy.

South Africa

In this study, the South African Medical Research Council analysed data from 1215 HIV positive pregnant women in their second or third trimester. Women were prospectively enrolled from six facilities in three provinces (Gauteng, KwaZulu-Natal and Mpumalanga) between October 2017 and May 2019.

Of 1215 women, 833 (68.6%) started IPT in pregnancy and 786 of these had known pregnancy outcomes. Less than 20% of the women who were not receiving IPT reported having taken it previously.

Over 90% of live births were recorded among the participants. In multivariate analysis, women receiving IPT were significantly more likely to have a live birth than IPT-unexposed women: 94.9% vs 92.6%, p=0.017. They were also less likely to have a miscarriage or a still birth.

Kenya

This was a retrospective chart review of antenatal and birth records of mother-infant pairs, attending two facilities in Kisumu province between 2015 and 202. The review was conducted by investigators from Emory University, Atlanta and University of Washington, Seattle.

They screened 779 medical records, of these, 576 mother-infant pairs had complete data. Women were a median age of 29 years and most were receiving ART (99%) with viral load <1000 copies/mL (97%). About one-third of women received IPT during pregnancy (27%), started a median gestational age of  23 weeks.

Adverse birth outcomes were frequent, occurring in 25.7% and 22.4% of IPT-unexposed births and IPT-exposed births, respectively.

There were slightly fewer preterm births among women receiving IPT than among those who did not: 18% vs 22%, NS.

There was no difference in the frequency of other adverse birth outcomes (low birth weight, congenital anomaly and perinatal death) between the two groups. Nor was there greater risk of composite adverse birth outcomes among women receiving IPT compared with those who did not. 

comment

These data are reassuring, particularly following concerns raised by the randomised IMPAACT P1078 TB that found adverse pregnancy outcomes to be higher among women starting IPT in pregnancy compared with postpartum. [3, 4]

In contrast, programmatic data from Western Cape, South Africa suggests that IPT was protective against poor pregnancy outcomes with lower proportions of miscarriage, stillbirth, low birth weight, and neonatal death. [5]

As did a sub-analysis of the Tshepiso cohort – a prospective observational study looking at maternal and infant outcomes among HIV positive women with and without TB in South Africa – although this was a secondary analysis with a small sample size. [6] 

Clearly IPT exposure in pregnancy needs continual monitoring in large cohorts.

And as investigators from the South African Medical Research Council noted:“With recent changes in TB and HIV treatment regimens, more research is needed to determine the safety of these therapies during each trimester of pregnancy and to evaluate pregnancy outcomes.”

References

1. Quincer E et al. The effect of antenatal isoniazid preventive therapy on birth outcomes in Western Kenya. 51st World Conference on Lung Health. 20–24 October 2020. Oral abstract OA-01-501-21.
2. Masuku S et al. Birth outcomes of pregnant women exposed to isoniazid preventive therapy. 51st World Conference on Lung Health. 20–24 October 2020. Oral abstract OA-01-502-21.
3. Clayden P. Isoniazid preventive TB therapy in pregnancy and postpartum: recommendations now need to be re-evaluated. HTB
   https://i-base.info/htb/33851
4. Gupta A et al. Isoniazid preventive therapy in HIV-infected pregnant and postpartum women. N Engl J Med 2019; 381:1333-1346. https://www.nejm.org/doi/full/10.1056/NEJMoa1813060
5. Kalk E et al. Safety and effectiveness of isoniazid preventive therapy in pregnant women living with Human Immunodeficiency Virus on antiretroviral therapy: an Observational Study Using Linked Population Data. Clinical Infectious Diseases. Published online 4 January 2020.
   https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciz1224/5695919
6. Clayden P. Isoniazid preventative therapy in HIV positive pregnant women not linked to poor outcomes. HTB. 28 March 2019.
   https://i-base.info/htb/35932

This report was first published online on 6 November 2020.