Table 2

Results of included studies reporting unintended pregnancy and pregnancy (intention undefined) in ascending order of incidence

Study	Incidence rate (per 100 person-years)	95% CI	Person-years of exposure	Duration (months)	Measurement of pregnancy	Frequency of measurement	Quality (%)
Unintended pregnancy
McClelland et al 77	7.2	4.5 to 10.9	305.4	12	Urine test	Monthly	40
Watson-Jones et al 44	11.8	9.7 to 14.5	796	30	Urine test	Quarterly on suspicion only	53
Gaffoor et al 42	13.4	6.1 to 25.4	67.2	24	Urine test	Quarterly	20
Behets et al 40	20.7	4.3 to 60.5	14.5	1	Urine test	Weekly	27
Braunstein et al 32	26.3	21.9 to 30.7	528.5	24	Serum test	6 monthly for 1 year+1 measurement in second year	60
Deschamps et al 33	27.3	23.3 to 31.7	615.6	18	Test (unspecified)	6 monthly	67
Chersich et al 34	28.0	22.6 to 34.3	335.8	12	Urine test	Quarterly	60
Peterson et al 46	51.7	44.9 to 59.3	400	12	Urine test	Monthly	40
Behets et al 39	53.0	21.0 to 110.0	13.2	2	Urine test	Monthly	40
Lara et al 41	59.6	41.7 to 82.5	60.4	4	Urine test	Monthly	40
Pregnancy (intention undefined)
Robb et al 51	2.0	1.4 to 2.9	1619.6	24	Self-report	Quarterly on suspicion only	21
McClelland et al 37	2.7	2.1 to 3.5	2259.3	15-year open cohort *	Urine test	Monthly on suspicion only	21
Bazzi et al 54	3.3	1.4 to 5.2	359.6	24	Self-report	6 monthly	43
Strathdee et al 43	5.9	4.1 to 8.4	540.1	12	Self-report	4 monthly	36
van Loggerenberg et al 52	8.5	5.6 to 11.5	376.5	24	Urine test	Monthly on suspicion only	36
Van Damme et al 48	8.6	6.7 to 10.8	837.5	≤24*	Urine test	Quarterly	29
Vielot et al 50	12.6	9.7 to 16.1	500.8	24	Urine test	Quarterly on suspicion only	50
Kaul et al 47	13.5	11.3 to 16.1	968.0	≤48*	N/A	N/A	21
Priddy et al 56	14.2	7.6 to 24.3	91.5	6	Urine test	Quarterly	36
Price et al 49	14.5	12.0 to 17.5	784.0	48	Urine test	Quarterly	43
Liu et al 53	15.2	10.4 to 21.5	210.3	6	Self-report	Quarterly	71
Kaewkungwal et al 36	15.8	13.0 to 19.0	721.0†	42	Urine test	N/A	43
Vandepitte et al 93	18.3	16.2 to 20.6	1467.0	≥24*	Urine test	N/A	50
Page et al 38	22.0	16.3 to 30.1	186.4	12	Self-report	Quarterly	50
Feldblum et al 35	23.4	20.6 to 26.5	1067.5	18	Urine test	6 monthly on suspicion only	43

↵*Duration varied for different participants.
↵†Person-time estimated by: (n_FSWs * yrs * retention) − (n_preg * yrs/2); where: n_FSWs, number of FSWs enrolled; yrs, study duration in years; retention, retention rate; n_p reg, number of women who became pregnant. We could not use the approach advocated by Vandenbrou c ke et al 95 as average follow-up time among FSWs was not known.
FSWs, female sex workers; N/A, not measured or reported, data not available from author.