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Table 2 Incidence of pregnancy among women enrolled in a HIV vaccine preparedness study in Masaka, Uganda (N = 389)

From: Contraceptive use, prevalence and incidence of pregnancy and associated factors among women participating in a vaccine preparedness cohort study in Masaka, Uganda, a retrospective secondary analysis

Baseline characteristics

N (%)

Pregnancy incidence

n (%)

PYO

IR/100 PYO

(95% CI)

Univariable analysis

Multivariable analysis

IRR (95% CI)

aIRR (95% CI)

Overall

389 (100)a

65 (17)b

301.3

21.6 (16.9–27.5)

  

Age group

    

P = 0.007

P = 0.014

 ≤ 24 years

214 (55)

46 (22)

162.2

28.4 (21.2–37.9)

2.08 (1.22–3.54)

1.97 (1.15–3.40)

 25 + years

175 (45)

19 (11)

139.1

13.7 (8.7–21.4)

Ref

Ref

Marital status

    

P = 0.264

 

 Single

206 (53)

35 (17)

169.0

20.7 (14.9–28.8)

Ref

 

 In relationship/married/cohabiting

97 (25)

22 (23)

78.4

28.0 (18.5–42.6)

1.35 (0.79–2.31)

 

 Divorced/separated/widowed

86 (22)

8 (9)

53.9

14.8 (7.4–29.7)

0.72 (0.33–1.54)

 

Education level

    

P = 0.111

P = 0.272

 ≤ Primary

250 (64)

36 (14)

195.5

18.4 (13.3–25.5)

Ref

Ref

 ≥ Secondary

139 (36)

29 (21)

105.8

27.4 (19.0–39.4)

1.49 (0.91–2.43)

1.32 (0.80–2.17)

Occupation

    

P = 0.190

 

 Otherc

70 (18)

9 (13)

66.4

13.6 (7.1–26.1)

Ref

 

 Female sex worker

219 (56)

29 (13)

135.6

21.4 (14.9–30.8)

1.58 (0.75–3.33)

 

 Salon/Lodge/Bar worker

100 (26)

27 (27)

99.4

27.2 (18.6–39.6)

2.00 (0.94–4.26)

 

Reported transactional sex

    

P = 0.559

 

 No

36 (9)

11 (31)

43.3

25.4 (14.1–45.8)

Ref

 

 Yes

353 (91)

54 (15)

258.0

20.9 (16.0–27.3)

0.82 (0.43–1.58)

 

Has anonymous/casual sex partners

    

P = 0.192

 

 No

10 (3)

5 (50)

13.1

38.2 (15.9–91.8)

Ref

 

 Yes

379 (97)

60 (16)

288.3

20.8 (16.2–26.8)

0.54 (0.22–1.36)

 

Sexual partner is older by ≥ 10 years

    

P = 0.982

 

 No

90 (23)

17 (19)

78.4

21.7 (13.5–34.9)

Ref

 

 Yes

299 (77)

48 (16)

222.9

21.5 (16.2–28.6)

0.99 (0.57–1.73)

 

Used recreational drugs (≤ 3 months)

    

P = 0.626

 

 No

330 (85)

55 (17)

261.2

21.1 (16.2–27.4)

Ref

 

 Yes

59 (15)

10 (17)

40.2

24.9 (13.4–46.3)

1.18 (0.60–2.32)

 

Had Sex after consuming alcohol (≤ 12 months)

    

P = 0.646

 

 No

171 (44)

26 (15)

129.0

20.2 (13.7–29.6)

Ref

 

 Yes

218 (56)

39 (18)

172.3

22.6 (16.5–31.0)

1.12 (0.68–1.84)

 

Number of partners (≤ 3 months)

    

P = 0.412

 

 ≤ 5

148 (38)

36 (24)

151.5

23.8 (17.1–32.9)

Ref

 

 ≥ 6

241 (62)

29 (12)

149.8

19.4 (13.4–27.9)

0.81 (0.50–1.33)

 

Diagnosed/treated for an STI (≤ 3 months)

    

P = 0.250

 

 No

202 (52)

30 (15)

160.6

18.7 (13.1–26.7)

Ref

 

 Yes

187 (48)

35 (19)

140.8

24.9 (17.9–34.6)

1.33 (0.82–2.17)

 

Reported contraceptive use at baseline

    

P = 0.370

 

 No

107 (28)

23 (22)

91.4

25.2 (16.7–37.9)

Ref

 

 Yes (Short term)d

69 (18)

16 (23)

63.0

25.4 (15.6–41.5)

1.01 (0.53–1.91)

 

 Yes (Long term)e

213 (55)

26 (12)

147.0

17.7 (12.0–26.0)

0.70 (0.40–1.23)

 
  1. Bold values in the first row represent overall totals. Other bold values represent p-values that are less than 0.05
  2. N: Number of participants with follow up data; PYO: person years of observation; IR: incidence rate; CI: Confidence interval; IRR: incidence rate ratio; aIRR: adjusted incidence rate ratio; Ref: Reference; STI: sexually transmitted infection
  3. aColumn percentages
  4. bRow percentages
  5. cOther includes professional/technical worker, sales/service worker, office clerk, student, subsistence fisheries worker etc.
  6. dCondom/oral contraceptive
  7. eInjectable/Implants/surgical/IUCD
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Reproductive Health

ISSN: 1742-4755