Table 2.

Primary Outcomes: Incidence and Relative Risk for 1-step vs 2-step GDM Screening

	Randomized Group		Pre-Planned Intention to Treat Analyses☆			IP Weighted ITT† Analyses
	1-step N=11922	2-step N=11870	Unadjusted	Adjusted for GDM	Adjusted for GDM, pre-planned covariates and factors related to non-adherence‡	Adjusted for GDM, pre-planned covariates and factors related to non-adherence‡
	n (%)	n (%)	RR (97.5% CI)§	RR (97.5% CI)§	RR (97.5% CI)§	RR (97.5% CI)§
Gestational diabetes ¶ ‖	1837 (16.5)	945 (8.5)	1.94 (1.79 - 2.11)	NA (NA)	1.93 (1.77 - 2.11)	1.93 (1.76 - 2.12)
Large for gestational age ☆☆ ‖	977 (8.9)	1015 (9.2)	0.95 (0.87 - 1.05)	0.93 (0.84 - 1.03)	0.94 (0.85 - 1.04)	0.92 (0.83 - 1.02)
Perinatal composite †† ‖	351 (3.1)	337 (3.0)	1.04 (0.88 - 1.23)	1.08 (0.90 - 1.30)	1.08 (0.89 - 1.31)	1.10 (0.91 - 1.35)
Gestational hypertension/preeclampsia ‡‡ ‖	1490 (13.6)	1472 (13.5)	1.00 (0.93 - 1.08)	0.96 (0.88 - 1.03)	0.98 (0.90 - 1.06)	0.98 (0.90 - 1.06)
Primary cesarean section §§ ‖	2826 (24.0)	2887 (24.7)	0.98 (0.93 - 1.02)	0.95 (0.91 - 1.00)	0.96 (0.91 - 1.02)	0.96 (0.91 - 1.02)

^☆Intention to Treat - compares pregnancies randomized to 1-step vs those randomized to 2-step

^†IP Weighted analyses were conducted to account for the non-adherence to randomized screening test. Stabilized weights were derived from modeling the probability of adhering to the randomly assigned screening test (details in SA Section S2.11)

^‡Pre-planned covariates include race/ethnicity, pre-pregnancy obesity and exceeding NAM weight gain guidelines.^22,23 Factors related to non-adherence include maternal age, nulliparity, race, Medicaid insurance, prior GDM, pre-existing hypertension, site, maternal obesity at 1^st prenatal visit, provider type, and randomized group

^§Widths of confidence intervals have not been adjusted to account for multiplicity and cannot be used to infer treatment effects

^¶Denominator is 11,127 for 1-step and 11,162 for 2-step. GDM is diagnosed by the 1-step approach (fasting 75g OGTT; IADPSG criteria), ⁹ and by Carpenter & Coustan criteria for the 2-step approach.¹ Pregnancies that did not receive either screening approach were 795 for 1-step and 708 for 2-step

^‖Denominators vary based on ascertainment method for each outcome. GDM includes only those pregnancies that received one of the two screening strategies. The maternal outcome of gestational hypertension/preeclampsia includes women without pre-existing hypertension prior to pregnancy. Primary cesarean section excludes women who left the health plan prior to delivery (167 for 1-step and 156 for 2-step). The perinatal outcomes include pregnancies for which the information was available in the maternal record (stillbirth and shoulder dystocia) or in newborn records that were matched to maternal records. Reasons for unmatched newborn records include: adopted infants, deliveries within and outside the health-plan where newborn is covered by other insurance, deliveries outside the health-plan and no reimbursement for newborn care is requested, mother left the health plan prior to delivery and no information is available for newborn. Total number of unmatched newborn records were 702 for 1-step and 709 for 2-step. Of the pregnancies with a diagnosis of shoulder dystocia in the maternal record, but no matching newborn record, 30 were 1-step and 21 were 2-step. Of the pregnancies with a diagnosis of stillbirth in the maternal record, but no matching newborn record, 32 were 1-step and 31 were 2-step. For LGA, in addition to excluding unmatched newborn records, birthweight was not available for 192 of 1-step and 175 of 2-step

^☆☆Denominator is 11,028 for 1-step and 10,986 for 2-step

^††Denominator is 11,281 for 1-step and 11,213 for 2-step. Perinatal composite was any of the following: stillbirth, neonatal death, shoulder dystocia, bone fracture or nerve palsy.⁸

^‡‡Denominator is 10,974 for 1-step and 10,894 for 2-step

^§§Denominator is 11,755 for 1-step and 11,714 for 2-step