TABLE 2

Maternal and Neonatal Characteristics and Risk of Unspecified Neonatal Apnea: Single Births in Sweden, 1999–2006 (N = 609 551)

Apnea
No.Rate/1000Odds Ratio (95% Confidence Interval)
CrudeAdjusted Model 1aAdjusted Model 2b
Maternal characteristics
    Maternal age, y
        ≤19252.71.56 (1.01–2.41)1.25 (0.79–1.99)1.17 (0.74–1.87)
        20–241161.7ReferenceReferenceReference
        25–292921.60.91 (0.73–1.13)1.08 (0.86–1.35)0.98 (0.78–1.23)
        30–342911.40.81 (0.65–1.00)1.05 (0.82–1.33)0.90 (0.71–1.15)
        ≥352072.01.13 (0.90–1.42)1.46 (1.13–1.88)1.11 (0.85–1.43)
    Height, cm
        130–1591082.21.35 (1.10–1.65)1.31 (1.0–1.61)1.06 (0.86–1.31)
        160–1747161.6ReferenceReferenceReference
        ≥175781.30.79 (0.63–1.00)0.81 (0.64–1.02)0.94 (0.74–1.19)
        Missing292.1
    Parity
        15212.01.70 (1.48–1.95)1.80 (1.55–2.08)1.30 (1.12–1.51)
        2–33401.2ReferenceReferenceReference
        4–9702.52.07 (1.60–2.68)1.60 (1.21–2.11)1.47 (1.10–1.95)
    Education, y
        ≤9881.91.32 (1.04–1.66)1.16 (0.89–1.52)0.95 (0.73–1.25)
        10–124631.71.16 (1.01–1.33)1.12 (0.97–1.30)1.03 (0.89–1.20)
        ≥133641.5ReferenceReferenceReference
        Missing161.7
Birth characteristics
    Cesarean delivery
        Yes3794.33.74 (3.28–4.26)1.19 (1.02–1.40)
        No5521.1ReferenceReference
    Gender
        Male5171.81.18 (1.04–1.34)1.12 (0.97–1.28)
        Female4141.5ReferenceReference
    Gestational age, wk
        ≤31359102.9156 (135–182)139 (115–167)
        32–361757.310.04 (8.38–12.04)9.49 (7.88–11.43)
        37–413620.7ReferenceReference
        ≥42350.70.98 (0.69–1.39)0.93 (0.65–1.34)
    SGAc
        Yes1178.45.76 (4.74–6.99)Reference
        No8141.50.85 (0.68–1.07)
  • Pregnancies with missing information for tobacco use (n = 39 692) were excluded from the analyses as well as dual users, which were too few (n = 480) to give raise to any cases.

  • a Model 1 was adjusted for maternal age, height, parity, education, and tobacco use.

  • b Model 2, in addition to maternal age, height, parity, education, and tobacco use, was adjusted for cesarean delivery, gender, gestational age, and SGA.

  • c SGA was defined as >2 SDs below the mean birth weight for gestational age according to the gender-specific Swedish fetal growth curve.19