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Table 1 Characteristics of the study population (N = 814)

From: Associations between maternal risk factors of adverse pregnancy and birth outcomes and the offspring epigenetic clock of gestational age at birth

Maternal characteristics Mean (SD) or N (%)
Pre-pregnancy risk factorsa
Maternal age at delivery, years 33.3 (5.8)
 Below 20 years, yes 22 (3.0%)
 Above 40 years, yes 115 (14.1%)
Pre-eclampsia in previous pregnancy, yes 178 (21.9%)
Intrauterine growth estriction in previous pregnancy, yes 85 (10.4%)
Gestational diabetes in previous pregnancy, yes 84 (10.3%)
 Diet treated 75 (9.2%)
 Insulin treated 9 (1.1%)
Pre-pregnancy body mass index kg/m2 27.4 (6.4)
 ≥30 kg/m2 287 (35.3%)
Pre-pregnancy chronic hypertension, yes 109 (13.4%)
Pre-pregnancy type 1 diabetes, yes 12 (1.5%)
Pre-pregnancy systemic lupus erythematosus, yes 2 (0.3%)
Sjögren’s syndrome, yes 11 (1.4%)
Previous pregnancy with fetal demise (>22 gestational weeks or over 500 g), yes 28 (3.4%)
Number of known pre-pregnancy risk factors  
 No known pre-pregnancy risk factors 79 (9.7%)
 1 or 2 pre-pregnancy risk factors 696 (85.5%)
 3 or more pre-pregnancy risk factors 31 (3.8%)
 Data not available 8 (1.0%)
Pregnancy disorders  
Gestational diabetes, yes 183 (22.5%)
 Diet treated 147 (18.1%)
 Insulin treated 36 (4.4%)
 Data not available on gestational diabetes treatment 2 (0.2%)
 Data not available on gestational diabetes diagnosis 1 (0.1%)
Hypertension spectrum pregnancy disorders, yes  
 Gestational hypertension 80 (9.8%)
 Pre-eclampsia 61 (7.5%)
  Early pre-eclampsia (diagnosis <34 weeks of gestation) 53 (6.5%)
  Late pre-eclampsia (diagnosis ≥34 weeks of gestation) 8 (1.0%)
  Non-severe pre-eclampsia 42 (5.2%)
  Severe pre-eclampsia 19 (2.3%)
 Chronic hypertension 134 (16.5%)
 Data not available 1 (0.1%)
Other characteristics
Education level  
 Lower secondary or less 359 (44.1%)
 Upper secondary 184 (22.6%)
 Tertiary 248 (30.5%)
 Data not available 23 (2.8%)
Parity  
 Primiparous 247 (30.3%)
 Multiparous 566 (69.5%)
 Data not available 1 (0.1%)
Smoking during pregnancy  
 Non-smoker 780 (95.8%)
 Quit during first trimester 26 (3.2%)
 Smoked throughout the pregnancy 8 (1.0%)
 Data not available 0
Alcohol use during pregnancy  
 No 588 (72.2%)
 Yes 117 (14.4%)
 Data not available 109 (13.4%)
Mode of delivery  
 Vaginal 640 (78.6%)
 Cesarean 173 (21.3%)
 Data not available 1 (0.1%)
Antenatal betamethasone treatment  
 No 750 (92.1%)
 Yes (n = 1 for 12 mg/24 h, n = 22 for 24 mg/24 h, n = 1 for 48 mg/24 h, n = 11 for no information on dose) 35 (4.3%)
Timing of antenatal betamethasone treatment, number of days before birth 33.4 (27.1)
 30 days or less before delivery 14 (1.7%)
 30 days or more before delivery 13 (1.6%)
 Data not available 29 (3.6%)
Neonatal characteristics
Sex  
 Girls 384 (47.2%)
 Boys 430 (52.8%)
 Data not available 0
Gestational age at birth, weeks 39.76 (1.60)
 Data not available 0
DNA methylation gestational age, weeks 38.45 (2.05)
 Data not available 0
Raw epigenetic gestational age difference, DNA methylation gestational age-gestational age −1.32 (1.85)
 Data not available 0
Absolute epigenetic gestational age difference, DNA methylation gestational age-gestational age in absolute values 1.78 (1.41)
 Data not available 0
Horvath DNA methylation age at birth, weeks 9.77 (19.51)
 Data not available 0
Birth weight, g 3549 (546)
  Small for gestational age, yesb 23 (2.8%)
 Data not available 1 (0.1%)
Birth length, cm 50 (2)
 Small for gestational age, yesb 21 (2.6%)
 Data not available 1 (0.1%)
Head circumference, cm 35 (2)
  Small for gestational age, yesb 14 (1.7%)
 Data not available 2 (0.3%)
Ponderal index, kg/m3 27.8 (2.7)
 Data not available 1 (0.1%)
Placenta weight, g 615 (134)
Cord blood pH  
 Arterial 7.26 (0.09)
 Venous 7.31 (0.08)
Apgar score  
 9–10 611 (75.1%)
 7–8 145 (17.8%)
 ≤6 47 (5.8%)
 Data not available 11 (1.4%)
  1. aPre-pregnancy risk factors served as inclusion criteria for the study as described [39]
  2. bSmall for gestational age indicates birth size for sex and gestational age SD ≤ −2 according to Finnish growth references [23]