Explanatory Variables

Category

Case

Control

Gestational Age

<37 weeks

74

14

≥37 weeks

57

251

Twining

Twin

23

9

Not twin

108

254

Congenital Anomalies

Present

1

1

Absent

130

262

Placental Abnormality

Present

0

0

Absent

131

263

Sex

Male

68

159

Female

63

105

Birth Interval

<2 yrs

43

71

≥2 yrs

56

155