Table 2 Clinical comparison of 776 twins and 348 singletons born at the hospital

Infant

 Male sex

373/776 (48.1%)

175/348 (50.3%)

RR = 0.96 (0.84-1.09)

 Birth weight; g (SD)

2271 (632)

3063 (583)

Diff = 791 (706–877)

Birth weight category

  > = 2500g

305/763 (40.0%)

302/343 (88.0%)

RR = 0.45 (0.41-0.51)

  2000-2499g

224/763 (29.4%)

27/343 (7.9%)

RR = 3.73 (2.54-5.47)

  <2000g

234/763 (30.7%)

14/343 (4.1%)

RR = 7.51 (4.42-12.8)

 Gestational age at birth; days (SD)

261 (35)

273 (28)

Diff = 12 (4–20)

 Prematurity

81/198 (41%)

38/162 (23%)

RR = 1.7 (1.2-2.5)

 Ballard score (SD)

37.9 (5.6)

42.6 (3.2)

Diff = 4.6 (3.9-5.4)

 Intertwin delivery interval; minutes (SD)

14.0 (31.0)

-

-

 Long intertwin delivery interval (>30 minutes)

54/686 (7.9%)

-

-

 Breech presentation at birth

123/773 (16%)

2/347 (0.6%)

RR = 27.6 (6.9-111)

 Caesarean section

177/773 (22.9%)

33/347 (9.5%)

RR = 2.41 (1.66-3.49)

 Age at discharge; days (SD)

4.2 (5.1)

1.5 (2.1)

Diff = 2.7 (2.2-3.2)

Mother

 Age; years (SD)

26.5 (5.5)

24.8 (5.8)

Diff = 1.7 (0.9-2.6)

 Age < 18 years

12/382 (3.1%)

33/347 (9.5%)

RR = 0.33 (0.17-0.63)

 Ethnicity

  Balante

104/387 (26.9%)

29/347 (8.4%)

P < 0.001

  Fula

82/387 (21.2%)

80/347 (23.1%)

  Pepel

58/387 (15.0%)

95/347 (27.4%)

  Mandinka

45/387 (11.6%)

14/347 (4.0%)

  Other

98/387 (25.3%)

129/347 (37.1%)

 No. of pregnancies (SD)

3.26 (1.76)

2.44 (1.58)

Diff = 0.82 (0.57-1.06)

 Primigravida

65/382 (17.0%)

127/346 (36.7%)

RR = 0.46 (0.36-0.60)

 Previous perinatal death

44/319 (13.8%)

42/219 (19.2%)

RR = 0.72 (0.49-1.06)

 BMI after birth; kg/m² (SD)

23.1 (4.18)

23.7 (4.41)

Diff = 0.59 (÷0.05-1.24)

 MUAC; mm (SD)

250 (30.9)

257 (35.8)

Diff = 7.1 (2.1-12.1)

 Family history of twinning

160/377 (42.4%)

98/345 (28.4%)

RR = 1.49 (1.21-1.83)

  Mother is twin herself

15/377 (4.0%)

15/345 (4.3%)

RR = 0.92 (0.45-1.84)

  Father is twin himself

36/377 (4.8%)

13/345 (3.8%)

RR = 1.27 (0.63-2.55)

  Mother has other twins

28/377 (7.5%)

3/345 (0.87%)

RR = 8.54 (2.62-27.9)

  Mother of mother has twins

96/377 (25.5%)

64/345 (18.6%)

RR = 1.37 (1.04-1.82)

  Mother of father has twins

60/377 (15.9%)

45/345 (13.0%)

RR = 1.22 (0.85-1.74)

 HIV infection

22/311 (7.1%)

12/282 (4.3%)

RR = 1.66 (0.84-3.30)

 Lack of schooling

167/380 (43.9%)

67/345 (19.4%)

RR = 2.26 (1.77-2.89)

 Unmarried

207/382 (54.2%)

172/346 (49.7%)

RR = 1.09 (0.95-1.25)

Pregnancy

 High BP (>140/90) at hospital arrival

30/149 (20.1%)

8/120 (6.7%)

RR = 3.02 (1.44-6.35)

 High BP (>140/90) during pregnancy

14/322 (4.3%)

4/315 (1.3%)

RR = 3.42 (1.14-10.3)

 Edemas

27/318 (8.5%)

1/316 (0.3%)

RR = 26.8 (3.7-197)

 Illness during pregnancy

53/375 (14.1%)

26/346 (7.5%)

RR = 1.88 (1.20-2.94)

 High risk pregnancy

17/264 (6.4%)

8/280 (2.9%)

RR = 2.25 (0.99-5.14)

 Unawareness of twin pregnancy

245/375 (65.3%)

-

-