Time trends in perinatal outcomes among HIV-positive pregnant women in Northern Tanzania: A registry-based study

Abstract

Introduction: Maternal HIV infection is associated with increased risk of having a preterm delivery, low birth weight baby, small for gestational age baby and stillbirth. Maternal use of combination antiretroviral treatment is also associated with preterm delivery and low birth weight, although the effects vary by the type of drugs and timing of initiation.

Objective: To examine time trends in adverse perinatal outcomes among HIV-positive compared with HIV-negative women.

Design: Registry-based cohort study.

Setting: Northern Tanzania, 2000-2018.

Study sample: Mother-baby pairs of singleton deliveries (n = 41 156).

Methods: Perinatal outcomes of HIV-positive women were compared with HIV-negative women during time periods representing shifts in prevention of mother-to-child transmission guidelines. Monotherapy was used as first-line therapy before 2007 while combination antiretroviral treatment was routinely used from 2007. Log binomial and quantile regression were used to analyze the data.

Main outcome measures: Preterm delivery, low birth weight, perinatal death, stillbirth, low Apgar score, transfer to neonatal care unit and small for gestational age.

Results: Overall, maternal HIV infection was associated with a higher risk of low birth weight and small for gestational age. Moreover, this pattern became more pronounced over time for low birth weight, the last time period being an exception. For other outcomes we found none or only a small overall association with maternal HIV infection, although a trend towards higher risk over time in HIV-positive compared with HIV-negative women was observed for preterm delivery and perinatal death. Quantile regression showed an increase in birth weight in babies born to HIV-negative women over time and a corresponding decline in birth weight in babies born to HIV-positive women.

Conclusion: Unfavourable trends in some of the selected perinatal outcomes were seen for HIV-positive compared with HIV-negative women. Potential side-effects of combination antiretroviral treatment in pregnancy should be further explored.

Fig 1. Final sample flow chart.

Fig 2. Distribution of categories of maternal HIV status for the whole study sample within each time period.

Fig 3. Adverse pregnancy outcomes among HIV-positive and HIV-negative pregnant women in Northern Tanzania, overall adjusted relative risks and by time period₁, 2004–2018.

ARR: Adjusted relative risk. Forest plot shows overall adjusted relative risks in our data from 2004–2018, and in time period 2–5, HIV-positive women compared with HIV-negative women. X-axis has log scale, and ARRs are adjusted for maternal age, marital status, parity (not in the last time period), current residence and education level. P-values in table are for trends in ARRS. ₁ Time periods: 2000–2003: Pilot phase before national PMTCT guidelines (excluded from these analyses); 2004–2006: WHO 2004 guidelines; 2007–2011: Revised WHO 2004 guidelines; 2012–2014: WHO Option A guidelines; 2015–2018: WHO Option B+ guidelines. ₂ Two variables that were used for defining early neonatal death were missing in the last time period.