Table 2.

Crude and adjusted relative risks of the association between maternal age and adverse pregnancy outcomes.

	Maternal age 30–34 years		Maternal age 35–39 years		Maternal age ≥40 years
	Crude OR [95% CI]	Adjusted ORa [95% CI]	Crude OR [95% CI]	Adjusted ORa [95% CI]	Crude OR [95% CI]	Adjusted ORa [95% CI]
Maternal Outcomes
Selective CS	1.53 [1.23 1.915]b	1.45 [1.14 1.83]b	2.48 [2.00 3.09]b	2.13 [1.67 2.71]b	4.21 [3.37 5.27]b	3.55 [2.75 4.58]b
Emergency CS	1.07 [0.83 1.37]	1.07 [0.82 1.40]	0.95 [0.74 1.23]	0.86 [0.65 1.14]	0.98 [0.77 1.27]	0.84 [0.63 1.13]
ART	2.91 [1.22 6.93]b	3.24 [1.33 7.90]b	13.87[6.37 30.19]b	17.10[7.59 38.51]b	19.06[8.81 41.21]b	24.95[11.04 56.39]b
Preeclampsia	1.68 [0.73 3.87]	2.32 [0.98 5.52]	3.80 [1.80 8.00]b	3.97 [1.81 8.74]b	7.46 [3.68 15.14]b	7.33 [3.43 15.68]b
Severe preeclampsia	1.51 [0.67 3.39]	2.37 [1.00 5.57]	2.56 [1.22 5.36]b	3.18 [1.42 7.10]b	2.98 [1.44 6.17]b	3.35 [1.51 7.45]b
Early onset preeclampsia	1.85 [0.68 5.02]	2.22 [0.77 6.41]	2.88 [1.13 7.35]b	2.63 [0.95 7.26]	2.53 [0.98 6.57]	2.03 [0.72 5.73]
Gestational Hypertension	1.20 [0.37 3.96]	1.15 [0.34 3.94]	5.15 [1.96 13.53]b	4.75 [1.70 13.29]b	2.63 [0.93 7.42]	2.52 [0.83 7.66]
GDM	1.30 [0.98 1.72]	1.39 [1.00 1.87]	2.78 [2.15 3.61]b	2.51 [1.89 3.33]b	3.26 [2.52 4.21]b	2.90 [2.16 3.88]b
GDM (lifestyle intervention)	1.15 [0.83 1.58]	1.20 [0.86 1.69]	2.50 [1.87 3.35]b	2.32 [1.69 3.19]b	4.10 [3.10 5.43]b	3.81 [2.77 5.24]b
GDM (on insulin)	1.61 [0.99 2.62]	1.77 [1.05 2.98]	2.46 [1.56 3.88]b	2.12 [1.27 3.52]b	0.67 [0.37 1.21]	0.55 [0.29 1.04]
ICP	0.64 [0.40 1.01]	0.84 [0.51 1.36]	0.87 [0.57 1.33]	1.14 [0.71 1.84]	0.83 [0.54 1.27]	1.13 [0.69 1.87]
Placental abruption	1.11 [0.45 2.76]	0.94 [0.36 2.46]	1.23 [0.51 2.98]	1.23 [0.46 3.30]	0.78 [0.29 2.09]	0.79 [0.26 2.41]
Placenta Praevia and Vasa Praevia	1.28 [0.87 1.87]	1.49 [0.99 2.25]	1.32 [0.90 1.93]	1.14 [0.75 1.73]	2.05 [1.44 2.92]b	1.60 [1.06 2.41]b
PPH	1.17 [0.72 1.89]	1.38 [0.82 2.33]	0.74 [0.43 1.27]	0.65 [0.36 1.17]	1.30 [0.81 2.09]	1.07 [0.62 1.85]
Abnormality of fetal presentation (non-cephalic)	1.16 [0.72 1.85]	1.18 [0.71 1.94]	1.54 [0.98 2.41]	1.34 [0.81 2.20]	1.57 [1.01 2.45]b	1.31 [0.78 2.20]
Fetal outcomes
Preterm birth (<37 weeks)	0.55 [0.39 0.77]b	0.65 [0.45 0.94]b	0.71 [0.51 0.97]b	0.70 [0.49 0.99]b	0.84 [0.62 1.14]	0.80 [0.56 1.15]
Low birthweight (<2500 g)	0.63 [0.40 0.98]b	0.76 [0.47 1.23]	0.83 [0.55 1.27]	0.81 [0.50 1.30]	1.01 [0.67 1.51]	0.93 [0.58 1.49]
Macrosomia (>4000 g)	1.45 [0.91 2.32]	1.38 [0.84 2.29]	1.10 [0.67 1.81]	0.98 [0.57 1.70]	0.94 [0.56 1.57]	0.81 [0.45 1.46]
IUGR	0.20 [0.04 0.91]b	0.21[0.04 1.02]	1.00 [0.41 2.41]	0.71 [0.25 1.98]	0.90 [0.37 2.24]	0.58 [0.20 1.73]
Apgar score < 7 at 5 minute	0.67 [0.11 4.00]	1.28 [0.18 8.88]	0.67 [0.11 4.00]	1.41 [0.20 10.13]	1.34 [0.30 6.02]	2.93 [0.49 17.70]
NICU admission	0.54 [0.34 0.86]b	0.62 [0.38 1.02]	0.78 [0.51 1.18]	0.72 [0.45 1.15]	0.86 [0.57 1.30]	0.73 [0.45 1.18]
Respiratory complications	2.91 [1.22 6.93]b	2.45 [0.99 6.06]	2.61 [1.08 6.30]b	2.05 [0.80 5.25]	2.62 [1.09 6.33]b	1.86 [0.70 4.92]

Note: CI: confidence interval; OR = odds ratio; ART: assisted reproductive techniques; GDM: gestational diabetes mellitus; ICP: Intrahepatic cholestasis of pregnancy; PPH: postpartum haemorrhage; IUGR: Intrauterine growth restriction; NICU: neonatal intensive care unit.

^aAdjusted for gravidity, parity, maternal baseline BMI, conceiving method, insurance, education, and residence. In the comparison of “conceived by ART”, the aforementioned confounding factors were considered except for conceiving method. ^bDenotes significance with a CI that does not cross 1

Maternal age 20–29 as the referent group. In the analysis of fetal outcomes, 2796 patients were analysed excluding pregnancies ending in stillbirth.