Table 1

Maternal CVD risk factors and established relationships with preterm birth

Risk factorReferenceSample sizeAdjusted OR or risk ratio (95% CI)
Total #Preterm #
(definition)
AgeCnattingius et al10499 94729 937
(<36 weeks)
OR 2.1 (1.9 to 2.2) for age >/=35 years in nulliparous non-smokers compared with multiparous non-smokers age 20 to 24 years
OR 2.3 (2.1 to 2.5) for age >/=35 years in nulliparous smokers compared with multiparous nonsmokers age 20 to 24 years
Meis et al112929120
(medically indicated <37 weeks)
OR 2.42 (1.57 to 3.74) for age >30 years compared with age </=30 years
Premkumar et al1223 4252069
(<37 weeks)
OR 1.29 (1.08 to 1.54) for age <25 years compared with age 30 to 34 years
OR 1.27 (1.05 to 1.55) for age >40 years compared with age 30 to 34 years
Race/ethnicityHarlow et al1314 948448
(spontaneous <37 weeks)
OR 2.0 (1.4 to 2.9) for black race compared with white
Meis et al112929120
(medically indicated <37 weeks)
OR 1.56 (1.02 to 2.40) for black ethnicity compared with white
Kistka et al14711 01514 611
(<37 weeks)
OR 2.21 (2.11 to 2.31) for black race compared with white
Premkumar et al1223 4252069
(<37 weeks)
OR 1.08 (0.89 to 1.30) for African-American compared with white
OR 1.04 (0.88 to 1.22) for Latina/Hispanic compared with white
OR 0.91 (0.79 to 1.05) for Asian/Pacific Islander compared with white
SmokingHarlow et al1314 948124
(medically indicated <37 weeks)
OR 1.1 (1.0 to 1.2) for smoking >5 cigarettes/day compared with no smoking
Bhattacharya et al157090318
(<37 weeks)
OR 1.47 (1.27 to 1.71) for smoking >10 cigarettes/day compared with no smoking
Premkumar et al1223 4252069
(<37 weeks)
OR 1.34 (0.99 to 1.80) for smoking compared with no smoking
HypertensionMeis et al112929120
(medically indicated <37 weeks)
OR 4.06 (2.29 to 7.22) for chronic hypertension compared with none
Sibai et al163499632
(<37 weeks)
OR 2.4 (2.1 to 2.7) for chronic hypertension compared with none
Premkumar et al1223 4252069
(<37 weeks)
OR 2.74 (2.28 to 3.29) for chronic hypertension compared with none
DiabetesHarlow et al1314 948124
(medically indicated <37 weeks),
448
(spontaneous <37 weeks)
OR 1.4 (1.1 to 1.8) for abnormal glucose tolerance testing in spontaneous preterm births compared with none
OR 2.2 (1.2 to 4.1) for abnormal glucose tolerance testing in medically indicated preterm births compared with none
Sibai et al163199555
(<37 weeks)
OR 2.7 (2.3 to 3.2) for pregestational insulin-dependent diabetes compared with none
Hedderson et al1746 2301956 (spontaneous <37 weeks)RR 1.23 (1.08 to 1.41) for abnormal glucose tolerance testing compared with none
RR 1.42 (1.15 to 1.77) for gestational diabetes compared with none
Premkumar et al1223 4252069
(<37 weeks)
OR 2.75 (2.18 to 3.47) for pregestational diabetes compared with none
ObesityHendler et al182910296
(spontaneous <37 weeks)
OR 0.57 (0.39 to 0.83) for obese (BMI>/=30 kg/m2) compared with non-obese (BMI <30 kg/m2)
McDonald et al19~1 095 834None given
(but defined as <37 weeks)
RR 1.24 (1.13 to 1.37) for overweight and obese compared with normal (BMI at least <24 kg/m2 for all included studies, with range given meta-analysis)
Cnattingius et al201 599 55167 059
(32–36 weeks)
OR 1.22 (1.18 to 1.27) for BMI 25 to 29.9 kg/m2, medically indicated
OR 0.98 (0.96 to 1.01) for BMI 25 to 29.9 kg/m2, spontaneous
OR 1.62 (1.54 to 1.71) for BMI 30 to 34.9 kg/m2, medically indicated
OR 1.01 (0.98 to 1.05) for BMI 30 to 34.9 kg/m2, spontaneous
OR 2.00 (1.84 to 2.18) for BMI 35 to 39.9 kg/m2, medically indicated
OR 1.06 (1.00 to 1.13) for BMI 35 to 39.9 kg/m2, spontaneous
OR 2.45 (2.15 to 2.79) for BMI >40 kg/m2, medically indicated
OR 1.13 (0.95 to 1.33) for BMI >40 kg/m2, spontaneous
With all groups compared with normal (BMI 18.5 to <25 kg/m2)
Premkumar et al1223 4252069
(<37 weeks)
OR 1.03 (0.91 to 1.17) for overweight (BMI 25 to 29.9 kg/m2) compared with normal (BMI 18 to 24.9 kg/m2)
OR 1.21 (1.04 to 1.40) for obese (BMI >30 kg/m2) compared with normal (BMI 18 to 24.9 kg/m2)
HyperlipidaemiaChatzi et al2162574
(<37 weeks)
RR 1.13 (0.91 to 1.40) for triglycerides per increase in 50 mg/dL
RR 1.08 (0.88 to 1.33) for HDL per increase in 15 mg/dL
RR1.17 (0.77 to 1.1.78) for LDL cholesterol per increase in 30 mg/dL
RR 1.24 (0.99 to 1.56) for total cholesterol increase in 40 mg/dL
Catov et al22938146
(34–37 weeks)
OR 1.38 (0.80 to 2.36) for fourth quartile total cholesterol (196 to 318 mg/dL) compared with second quartile (156–172)
OR 1.86 (1.10 to 3.15) for first quartile total cholesterol (94 to 155 mg/dL) compared with second quartile (156–172)
OR 1.07 (0.63 to 1.83) for fourth quartile LDL (124 to 233 mg/dL) compared with second quartile (89–104)
OR 1.60 (0.96 to 2.68) for first quartile LDL (26 to 88 mg/dL) compared with second quartile (89–104)
OR 0.99 (0.58 to 1.67) for fourth quartile triglycerides (78 to 318 mg/dL) compared with second quartile (44–57)
OR 1.13 (0.68 to 1.88) for first quartile triglycerides (16 to 43 mg/dL) compared with second quartile (44–57)
OR 1.52 (0.92 to 2.49) for fourth quartile HDL (64 to 118 mg/dL) compared with second quartile (47–54)
OR 1.05 (0.62 to 1.79) for first quartile HDL (25 to 46 mg/dL) compared with second quartile (47–54)
Harville et al23114267
(<37 weeks)
RR 1.11 (0.84 to 1.46) for total cholesterol as continuous variable
RR 0.92 (0.73 to 1.17) for HDL as continuous variable
RR 1.13 (0.86 to 1.48) for LDL as continuous variable
RR 1.10 (0.84 to 1.42) for triglycerides as continuous variable
Magnussen et al244990272
(<37 weeks)
OR 1.3 (0.9 to 2.0) for fifth quintile total cholesterol (5.7 to 9.9 mmol/L) compared with first quintile (2.1 to 4.1 mmol/L)
OR 1.4 (0.9 to 2.2) for first quintile HDL (1.9 to 3.1 mmol/L) compared with first quintile (0.6 to 1.2 mmol/L)
OR 1.3 (0.8 to 2.2) for fifth quintile triglycerides (1.6 to 9.6 mmol/L) compared with first quintile (0.2 to 0.6 mmol/L)
Alleman 2013402699200
(<37 weeks)
OR 1.03 (0.89 to 1.19) for total cholesterol as continuous variable
OR 1.01 (0.88 to 1.17) for LDL as continuous variable
OR 0.96 (0.83 to 1.11) for HDL as continuous variable
OR 1.02 (0.88 to 1.17) for triglycerides as continuous variable
  • ORs or RRs with p<0.05 are highlighted in bold.

  • BMI, body mass index; CVD, cardiovascular disease; HDL, high-density lipoprotein; LDL, low-density lipoprotein.