Adverse birth outcomes with diabetes and hypertensive disorders in pregnancy

Polly Clayden, HIV i-Base

Women living with HIV with diabetes or hypertensive disorders in pregnancy are more likely to have adverse birth outcomes than women without these complications.

These data from the Integrated Screening Outcomes Surveillance Service (ISOSS) were presented at the BHIVA spring conference 2023. [1, 2]

Diabetes and hypertensive disorders in pregnancy are associated with adverse birth outcomes. Adults with HIV are more likely to have diabetes then those without (there is conflicting evidence with hypertension).

The study aim was to estimate the prevalence and to compare maternal characteristics and birth outcomes in pregnant women living with HIV with and without these comorbidities.

ISOSS collects population level data on all pregnant women living with HIV in the UK (England only from 2020).

The evaluation included pregnancies with deliveries between 2010 to 2020 at 24 gestational weeks or more. Diabetes was defined as pre-existing or gestational diabetes and hypertensive disorders were: pre-eclampsia, hypertension, or pregnancy-induced hypertension. The comparator group were pregnancies in women living with HIV without these complications.

The study compared the following outcomes: preterm birth (<37 weeks), low birthweight (<2.5 kg), small for gestational age (<10th percentile, INTERGROWTH-21) and birthweight z-scores (INTERGROWTH-21).

During the study period, there were 10401 pregnancies reported in 9016 women. Diabetes was reported in 554 pregnancies to 503 women and 92% of these cases were gestational diabetes. Hypertensive disorders were reported in 511 pregnancies to 458 women and 75% of these were pre-eclampsia. A small proportion had both complications: 46 pregnancies to 43 women. There were 8232 pregnancies among 5937 women in the comparator group.

Prevalence of diabetes increased over time. Between 2010 and 2020 this changed from 2.7% to 10.3% (p<0.001). There was a notably steeper incline from 2015 onward. Hypertensive disorder prevalence remained similar over the 10 year period: 3.9% to 5.8% (p=0.07).

Risk factors for diabetes, hypertensive disorders or both were: aged 35 years and above, black African or Caribbean, first pregnancy and ART at conception.

Women aged 35 and above were 32.4% of the pregnant population in 2010 vs 52.8% in 2020 (p<0.0001).

Emergency Caesarean section occurred in 1 in 3 pregnancies among women with diabetes, 1 in 2 in those with hypertensive disorders compared to 1 in 5 in the comparator group.

Stillbirth was 4.8 and 12 times more prevalent than the comparator in the diabetes and hypertensive disorders groups respectively: 1.3% and 3.1% vs 0.26% (comparator).

Preterm birth occurred in 1 in 5 pregnancies among women with diabetes and 2 in 5 in those with hypertensive disorders compared to less than 1 in 10 (7.7%) in the comparator group.

Almost half (46%) of infants born to women with hypertensive disorders were low birth weight. This proportion was 13.4% among the infants born to women with diabetes and 8.8% in the comparator group.

One in 5 (21.1%) of infants born to women with hypertensive disorders were small for gestational age. This compares with 6% in the diabetes and 8.2% in the comparator groups.

The prevalence of comorbidities has changed significantly over time with implications for birth outcomes. Further research is required to understand possible mechanisms and optimise pregnancy outcomes for women.

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Maternal age may account for the increase in diabetes in this cohort, although weight might also be a driver and these data were not previously routinely collected. ISOSS are now collecting BMI and other weight indices.  

The study was not able to assess the contribution of ART to the prevalence of these comorbidities. A number of evaluations are currently looking at hypertensive disorders in adults on ART in large studies, including comparisons of different antiretrovirals – notably in African populations and in pregnancy. Some of these data will be presented at the upcoming IAS conference.  

Apart from ART at conception the risk factors are similar to those in the general population.

References

1. Bukasa L et al. Diabetes and hypertensive disorders in pregnant women living with HIV in the UK and Ireland. BHIVA 2023 spring conference. Gateshead, UK. 24–26 April 2023.  Oral abstract O11.
   https://www.bhiva.org/file/645ba42b19006/O11.pdf
2. Integrated Screening Outcomes Surveillance Service (ISOSS)
   https://www.ucl.ac.uk/integrated-screening-outcomes-surveillance/integrated-screening-outcomes-surveillance-service-isoss

This report was first published on 19 June 2023.