Table 3:

Risk of perinatal outcomes associated with fetal reduction

Perinatal outcome	Reduced to twin pregnancy v. unreduced triplet pregnancy			Reduced to singleton pregnancy v. unreduced twin pregnancy
	All births		ART only	All births		ART only
	Crude rate ratio (95% CI)	Adjusted rate ratio* (95% CI)	Adjusted rate ratio† (95% CI)	Crude rate ratio (95% CI)	Adjusted rate ratio* (95% CI)	Adjusted rate ratio† (95% CI)
Preterm (< 37 wk)	0.62 (0.40–0.78)	0.66 (0.54–0.80)	0.68 (0.56–0.84)	0.40 (0.25–0.65)	0.40 (0.25–0.66)	0.42 (0.23–0.77)
Very preterm (< 32 wk)	0.37 (0.18–0.76)	0.40 (0.20–0.78)	0.92 (0.17–0.59)	1.24 (0.58–2.65)	1.36 (0.64–2.92)	1.44 (0.53–3.89)
Low birth weight (< 2500 g)	0.58 (0.47–0.72)	0.59 (0.49–0.72)	0.58 (0.46–0.72)	0.50 (0.30–0.81)	0.51 (0.32–0.82)	0.39 (0.19–0.78)
Very low birth weight (< 1500 g)	0.42 (0.21–0.82)	0.43 (0.23–0.81)	0.39 (0.22–0.67)	1.07 (0.42–2.76)	1.19 (0.45–3.04)	0.94 (0.25–3.51)
Small for gestational age	1.89 (1.09–3.28)	2.14 (1.18–3.88)	2.29 (1.20–4.39)	1.07 (0.62–1.87)	1.13 (0.65–1.93)	0.68 (0.27–1.70)
5-min Apgar score ≤ 7	0.58 (0.28–1.19)	0.60 (0.28–1.30)	0.37 (0.15–0.92)	1.06 (0.50–2.25)	1.16 (0.55–2.46)	1.23 (0.51–2.94)
Serious neonatal morbidity or perinatal death	0.50 (0.24–1.02)	0.50 (0.24–1.07)	0.35 (0.18–0.67)	1.39 (0.65–2.95)	1.57 (0.74–3.33)	1.60 (0.64–3.98)

Note: ART = assisted reproductive technology, CI = confidence interval.

^*Adjusted for infant sex, maternal age, parity, pre-pregnancy weight, socioeconomic status and use of assisted reproductive technology.

^†Adjusted for infant sex, maternal age, parity, pre-pregnancy weight and socioeconomic status.