Table 2.

Study characteristics of studies that investigated the association between BV and pregnancy outcomes of pregnant women in the sub-Saharan African region.

References	Country	Study design	Study population	Follow-up	Methods to detect BV	Number of participants		Maternal age (years)	GA at sampling (weeks)	Gravidity/parity	Other genital infections (n)	Women infected with HIV	Confounding factors considered
						BV+	BV–
Govender et al. (74)	Durban, South Africa	Prospective cohort study	Pregnant women on first visit to ANC (<30 wks) with no vaginal discharge	Followed until delivery	Nugent score	88	80	24 (16–44)	NR	Gr: NR Parity: 3 (0–6)	–Candida: 16 – CT: 14 NG: 5 TP: 20 - TV: 35	9 (5%)	None
Odendaal et al. (76)	Western Cape, South Africa	Randomized control trial	Pregnant women (15–26 weeks) who had had a previous preterm labor or mid-trimester miscarriage. Gr = 1: 464 Gr ≥ 2: 491**	Patients were followed up for the rest of the pregnancy, labor, and puerperium	Gram stain, wet mount smear, amine test, Spiegel test. 3 of 5 Amstel criteria	277 – Gr = 1: 150 – Gr ≥ 2: 127	678 – Gr = 1: 314 – Gr ≥ 2: 364	BV+ group: – Gr = 1 treated: 21.2 ± 5.0 – Gr = 1 placebo: 22.3 ± 4.9 – Gr ≥ 2 treated: 27.1 ± 4.5 – Gr ≥ 2 placebo: 27.9 ± 5.4 BV- group: Gr = 1: 21.3 ± 5.2 - Gr ≥ 2: 28.4 ± 5.4	“Soon after enrollment”: BV + group: –Gr = 1 treated: 20.2 ± 3.1 – Gr = 1 placebo: 20.4 ± 3.0 – Gr ≥ 2 treated: 27.1 ± 4.5 Gr ≥ 2 placebo: 27.9 ± 5.4 BV- group: - Gr = 1: 20.2 ± 2.8 - Gr ≥ 2: 19.7 ± 3.0	Gr (n): –Primigravidae: 464 – Multigravidae: 491 Parity: NR	NR	NR	None
Schoeman et al. (78)	South Africa	Double-blind randomized placebo-controlled trial Intervention: Vitamin C	Pregnant women (14–26 weeks) with a history of a previous mid-trimester miscarriage or a preterm delivery	Until delivery	Nugent score	82	116	Vitamin C group: 28 (18–44) Placebo group: 28 (19–45)	NR (samples were taken until 34 weeks)	Gr:–Vitamin C group: 3 (2–8) – Placebo group:3 (2–7) Parity: – Vitamin C group: 1 (0–6) - Placebo group: 2 (0–4)	NR	NR	None
Watson-Jones et al. (75)	Mwanza, United Republic of Tanzania	Prospective cohort study	Women attending antenatal clinic	Followed up to the point of delivery	Nugent's score	459	1,077	23.8 (Mean)	25.4 ± 6.1	Gr (n): 1–2: 828 3–5: 566 ≥ 6: 142 Parity: NR	–Candida: 454 – CT: 114 NG: 33 - TV: 315	177 (11.7%)	*
Shayo et al. (73)	Mwanza, Tanzania	Cross-sectional descriptive study	Delivering women	No follow-up	Nugent's score	81	202	26 (Median)	NR	Gr: NR Parity: 2 (Median)	Candida: 74	15 (5.3%)	None
Slyker et al. (79)	Nairobi, Kenya	Retrospective cohort study	HIV-infected women with ≥28 weeks	Follow-up until 1 year after delivery	Nugent score	144	241	25 (22–28)	32 weeks	Gr: NR Parity: 1 (1–2)	–Candida: 124 – CT: 16 NG:8 TP: 10 TV: 65 Any STI: 88	All women were HIV infected	Univariate analysis and stepwise logistic regression
Nakubulwa et al. (70)	Uganda	Unmatched case–control study	Cases: women with confirmed PROM, ≥28 weeks. Controls: Women without PROM in latent phase of labor	No follow-up	Gram stain	2	172	Cases: Age: (n) <20: 10 20–35: 73 ≥35: 4 Controls: Age: (n) <20: 9 20–35: 69 ≥35: 9	NR	Gr cases (n): 1: 31 2–4: 47 >5: 9 Gr controls (n): 1:31 2–4: 48 > 5: 8 Parity: NR	–Candida: 61 – CT: 6 – NG: 1 – TP: 0 TV: 25 -HSV-Ab: 95 -HSV-ELISA: 51	24 (13.8%)	No further analysis was done for BV due to few numbers
Afolabi et al. (77)	Lagos State, Nigeria	Prospective observational study	Healthy pregnant women (14–36 weeks)	Until 1 week after delivery	Nugent score	64	182	30.9 (20–44) [Mean (range)]	NR	Gr: NR Parity: (n) 1: 92 ≥2: 154	NR	0	None
Aderoba et al. (80)	Benin City, Nigeria	Unmatched case–control study	Cases: women with PTL (28–37 weeks). Controls: women with term labor (≥37 weeks)	No follow-up	Nugent score	22	60	Cases: 29.2 ± 5.7 Controls: 29.7 ± 3.8	NR	Gr: NR Parity: 1.89 (0–5) [Mean(range)]a	NR	NR	Marital status
Aduloju et al. (72)	Ado-Ekiti, Nigeria	Descriptive cross-sectional study	Pregnant women with abnormal vaginal discharge	Until delivery	Spiegel's method, 3 of 4 Amsel criteria, Nugent score	60	302	BV+: 26.24 ± 6.14 BV–: 28.13 ± 4.38	BV+: 25.27 ± 3.42 BV–: 26.63 ± 2.52	Gr: NR Parity: BV+: 2.7 ± 2.3 BV–: 3.0 ± 1.1	NR	NR	None
Warr et al. (71)	Nyanza region, Kenya	Nested longitudinal cohort study	Pregnant women (HIV uninfected)	9 months postpartum	Nugent score	271	950	22 (19–27)	NR	Gr: 2 (1–4) Parity: 2 (1–3)	–Candida: 302 – CT: 65 – NG: 29 – TP: 10 – TV: 79	0	None

Data are reported as means ± SD, median (IQR), median (range), or n (%), unless otherwise specified.

Ab, antibody; ANC, antenatal care; ANC, antenatal clinic; BV, bacterial vaginosis; BW, birth weight; CT, Chlamydia trachomatis; EGA, estimate gestational age; GA, gestational age; Gr, gravidity; HIV, human immunodeficiency virus; HSV-2, human simplex virus type 2; IQR, interquartile range; IUFD, intrauterine fetal death; IUGR, intrauterine growth restriction; IUI, intrauterine infection; LBW, low birth weight; NG, Neisseria gonorrhoeae; NND, neonatal death; NR, not reported; PND, perinatal death; PROM, premature rupture of the membranes; PTB, preterm birth; PTL, preterm labor; SD, standard deviation; SGA, small for gestational age; STI, sexual transmitted infection; TP, Treponema pallidum.

^*Stillbirth: adjusted for age, height, gravidity, history of stillbirth, HIV at delivery, and maternal anemia. Prematurity: adjusted for age, occupation, gravidity, HIV at delivery, maternal malaria. LBW: adjusted for age, tribe, occupation, height, gravidity, Chlamydia trachomatis at recruitment, HIV at delivery and maternal malaria. IUGR: adjusted for age, tribe, occupation, height, gravidity, baby's sex, maternal malaria and HIV at delivery.

^**Analysis was done for primigravidae and multigravidae separately.