Endpoint prevalence ranges

This section provides example prevalence ranges for key pregnancy endpoints of high importance in research on TB drugs used in pregnancy.

Table 5.3 provides estimates for women living with HIV and exposed to TB preventive treatment, using isoniazid (1, 37–39).
Table 5.4 provides estimates for women with any TB (pulmonary (PTB), extrapulmonary (EPTB)), drug-susceptible or drug-resistant TB in medium/high TB incidence settings (see Annex 2 of the WHO consensus statement) (40)

The estimates were derived preferentially, but not exclusively from low- and middle-income countries, 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 outcome estimates to inform sample size calculations for various comparisons and study designs.

In addition, prevalence levels of most of the endpoints differ substantially between populations; hence, consideration of any findings in the context of locally relevant comparator endpoint prevalence data is important, where possible.

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

Table 5.3. Maternal mortality, and pregnancy and infant outcome prevalence ranges for women living with HIV and exposed to isoniazid preventive treatment
Outcome	Range (%)
Fetal demise (miscarriage or stillbirth)	7.8%–36.1% (1)
Preterm <37 weeks (in live births)	10.1%–26.3% (1,2)
Low birth weight <2500 g (in live births)	8.7%–31.6% (1,2)
Neonatal death (through 28 days)	2.1% (3)
Combined adverse pregnancy outcome (fetal demise, preterm birth, low birth weight)	23%–63% (1)
Maternal mortality (during pregnancy or postpartum)	0%–1.6% (2,4)
Congenital anomalies in studies that include only major structural abnormalities of prenatal origin that affect health, survival, physical or cognitive functioning of the individual	1.4%–2.3% (2,4)

Table 5.4. Maternal mortality, and pregnancy and infant outcome prevalence ranges for women with any TB type (PTB, EPTB), drug-susceptible, or drug-resistant TB in medium/high TB incidence settings
Outcome	Range (%)*
Miscarriage, <20 weeks’ gestation, n = 9	0%–12.9%
Stillbirth (ranging from ≥20 to ≥28 weeks’ gestation), n = 10	0%–9.6%
Preterm <37 weeks (in live births), n = 11	3.7%–70%
Low birth weight <2,500 g (in live births), n = 9	13.7%–63.6%
Small-for-gestational age (in live births), n = 5	11.1%–43.2%
Neonatal death (through 28 days)	N/A
Infant mortality (through 1 year), n = 4	0%–8.6%
Maternal mortality (during pregnancy or postpartum)	0%–29.4% 0%–13.2%*
* Prevalence ranges based on Chaisson LH, Cox SR. WHO-commissioned systematic review on TB and pregnancy [unpublished], personal communications, where n is the number of studies included in the review for the corresponding outcome. Includes only women with any TB (PTB, EPTB) or drug-susceptible TB. *** Included only women with multidrug-resistant/rifampicin-resistant TB. N/A:** not available.