Table 4.

Adjusted prenatal care coefficients in birth weight regression models for the Natality samples

	Non-isolated clefts		Isolated clefts		No clefts
	Regression Coefficient (Standard Error)	P value	Regression Coefficient (Standard Error)	P value	Regression Coefficient (Standard Error)	P value
Gestational age not adjusted for in the regression as a covariate
Model 1: Assuming a linear effect of prenatal visits
Number of visits	50.58 (9.43)	< 0.0001	21.30 (3.73)	< 0.0001	16.32 (0.28)	< 0.0001
Model 2: Assuming a non-linear effect of prenatal visits
Number of visits	97.39 (23.94)	< 0.0001	53.91 (10.79)	< 0.0001	55.26 (0.683)	< 0.0001
Number of visits squared	−1.911 (0.899)	0.034	−1.313 (0.408)	0.001	−1.474 (0.0236)	< 0.0001
Model 3: Using Kessner Index instead of prenatal visits (effects relative to adequate care)
Inadequate prenatal care	−89.62 (151.3)	0.554	−31.19 (66.98)	0.642	−94.29 (4.97)	< 0.0001
Intermediate prenatal care	−263.1 (104.1)	0.012	−118.3 (37.9)	0.002	−33.27 (2.90)	< 0.0001
Gestational age adjusted for in the regression as a covariate
Model 1: Assuming a linear effect of prenatal visits
Number of visits	16.77 (8.30)	0.044	8.00 (3.34)	0.017	4.59 (0.24)	< 0.0001
Model 2: Assuming a non-linear effect of prenatal visits
Number of visits	44.49 (20.50)	0.031	28.74 (9.575)	0.003	20.74 (0.577)	< 0.0001
Number of visits squared	−1.118 (0.756)	0.140	−0.831 (0.360)	0.021	−0.606 (0.0198)	< 0.0001

Note: Regression models included several socioeconomic, demographic, and maternal health covariates described in the Table II.