Pregnancy outcomes: prevalence estimates

This page provides example prevalence ranges for key pregnancy endpoints of high importance in research on HIV agents used in pregnancy.

  • Table 1 provides general population estimates.
  • Table 2 provides estimates for women living with HIV.

The estimates were derived preferentially but not exclusively from low- and middle-income countries (LMICs), in particular sub-Saharan Africa, and from studies conducted since 2010. Prevalence estimates were obtained from key pregnancy studies, systematic reviews and meta-analyses, rather than through an exhaustive review of the literature.

Important: These tables are intended to provide reasonable pregnancy outcome estimates to inform sample size calculations for various comparisons and study designs.

The estimates should not be taken to be definitive. Where possible, investigators should use the most relevant local estimates (in terms of location, population, calendar year, method of ascertainment and definition) in planning their analyses and their own sample size calculations.

Also, prevalence of most of these endpoints differs substantially between populations; hence, consideration of any findings in the context of locally relevant comparator endpoint prevalence data is important, whenever possible.

Table 1. Pregnancy outcome prevalence ranges for the general population 

OutcomeRange (%)
Miscarriage, <20 weeks’ gestation* 15%-30%*(1,2)
Stillbirth (ranging from ≥20 to ≥28 weeks’ gestation)0.3%-2.5% (3-7)
Preterm <37 weeks (in live births)6%-22% (4-6,8-12)
Low birthweight <2,500g (in live births)10%-14% (4,5,7,11,12)
Small for gestational age (SGA) (in live births)16%-30% (5,13,14)
Neonatal death (through 28 days)1.7%-3.2% (5,6,9,12,15)
Infant mortality (through 1 year)2.6%-3.1% (15,16)
Congenital anomalies1%-4.3% (12,17-20)
Congenital anomalies in studies that include only major structural abnormalities of prenatal origin that affect health, survival, physical or cognitive functioning of the individual0.4%-0.7 % (21-25)
Neural tube defects8-50 per 10,000 (26-28)
Maternal mortality (during pregnancy or within 42 days of delivery)<1%-5% (12,29,30)

* These estimates are based on data from Europe and North America only; data not available for miscarriage rates <28 weeks’ gestation

Table 2. Pregnancy outcome prevalence ranges for women living with HIV

OutcomeRange (%)
Miscarriage, <20 weeks’ gestation* 20%-37%* (31,32)
Stillbirth (ranging from ≥20 to ≥28 weeks’ gestation)1%-4% (7,31,33-37)
Preterm <37 weeks (in live births)6%-22% (4-6,8-12)
Low birthweight <2,500g (in live births)12%-24% (7,34,38,41,43,44)
Small for gestational age (SGA) 10%-25% (7,34,37,40,42,43)
Neonatal death (through 28 days)1-4% (33,45,46)
Infant mortality (through 1 year)1-7% (33)
Congenital anomalies2-6% (34,47,48)
Congenital anomalies in studies that include only major structural abnormalities of prenatal origin that affect health, survival, physical or cognitive functioning of the individual0.4%-0.6% (21-25)
Neural tube defects8-50 per 10,000 (21,28,49)
Maternal mortality (during pregnancy or within 42 days of delivery)2%-6% (29,30,33)
Combined outcome (PTB, SGA, LBW and neonatal death)30-35% (50,51)

*Among persons conceiving on ART (primarily older ARV regimens)

References

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