. 2023 Oct 3;330(16):1547–1556. doi: 10.1001/jama.2023.19869

Table 3. Neonatal Weight, Height, and Size.

Outcome	No./total (%)^a		Unadjusted risk difference (95% CI)	Unadjusted relative risk (95% CI)	P value^b	P value^c
Outcome	Metformin (n = 262)	Placebo (n = 262)	Unadjusted risk difference (95% CI)	Unadjusted relative risk (95% CI)	P value^b	P value^c
Neonatal size
Gestational age at birth, mean (SD), wk^d	39.1 (1.5)	39.1 (1.6)	0 (−0.3 to 0.2)		.66
Birth weight, mean (SD), g	3393 (527)	3506 (510)	−113 (−201 to −24)		.01	.005
Birth weight >4000 g	20/262 (7.6)	39/262 (14.8)	−7.2% (−12.6% to −1.8%)	0.5 (0.3 to 0.9)	.02	.02
Birth weight >90th percentile	17/261 (6.5)	39/261 (14.9)	−8.4% (−13.7% to −3.2%)	0.4 (0.3 to 0.8)	.003
Birth weight <2500 g	16/262 (6.1)	9/262 (3.4)	2.7% (−1% to 6.3%)	1.8 (0.8 to 4.0)	.12	.12
Birth weight <10th percentile	15/261 (5.7)	7/261 (2.7)	3.0% (−0.4% to 6.5%)	2.1 (0.9 to 5.2)	.13
Head circumference, mean (SD) [No.], cm	34.7 (1.6) [253]	34.7 (1.8) [253]	0 (−0.3 to 0.3)		.82	.60
Crown-heel length, mean (SD) [No.], cm	51.0 (3.2) [253]	51.7 (3.3) [253]	−0.7 (−1.3 to −0.2)		.02	.02
Abdominal circumference, mean (SD) [No.], cm	33.4(2.4) [154]	33.3 (2.8) [157]	0.1 (−0.5 to 0.7)		.72	.81
Mid-upper-arm circumference, mean (SD) [No.], cm	11.0 (1.0) [154]	11.1 (1.1) [156]	−0.1 (−0.3 to 0.1)		.47	.33
Ponderal index mean, mean (SD) [No.]^e	2.6 (0.4) [253]	2.6 (0.5) [253]	0 (−0.1 to 0.1)		.68
Neonatal morbidities^f
Need for NICU care	41/262 (15.6)	33/262 (12.6)	3% (−2.9% to 9%)	(0.8 to 1.9)	.38
Respiratory distress requiring respiratory support	24/262 (9.2)	18/262 (6.9)	2.3% (−2.4% to 6.9%)	1.3 (0.7 to 2.4)	.42
Jaundice requiring phototherapy	1/262 (0.4)	0	0.4% (−.4% to 1.1%)		>.99
Major congenital anomalies	10/262 (3.8)	7/262 (2.7)	1.1% (−1.9% to 4.2%)	1.5 (0.6 to 3.7)	.62
Apgar score <7 at 5 min	1/262 (0.4)	1/260 (0.4)	0% (−1% to 1%)	1 (0.1 to 15.8)	>.99
Neonatal hypoglycemia (<2.6 mmol/L on ≥1 occasion <60 min postdelivery)	36/262 (13.7)	34/262 (13)	0.7% (−5.1% to 6.6%)	1.1 (0.7 to 1.6)	.90

Abbreviation: NICU, neonatal intensive care unit.

^{^a}

Numeric values are reported as No./total (%) unless otherwise indicated.

^{^b}

P values for birthweight (in grams), birth weight >4000 g, birth weight <2500 g, head circumference, crown-heel length, abdominal circumference, and mid-upper-arm circumference were derived from a statistical model that adjusts for the infant’s sex and maternal height and weight at randomization. The other P values in this column pertain to unadjusted comparisons.

^{^c}

P values were derived from a model that adjusts for gestational age at birth, in addition to the infant’s sex and maternal height and weight at randomization.

^{^d}

Although gestational age at birth is determined postrandomization, no evidence was found to support an effect of metformin on gestational age at birth.

^{^e}

Ponderal index is calculated as 100 × weight (grams)/(crown-heel length)^3. This index is a measure of relative body size (similar to measuring body mass index), with larger values indicating larger body size relative to height (range, 1.5 to 7.3).

^{^f}

A more complete listing of neonatal morbidities is given in eTable 2 in Supplement 2.