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. 2009 Mar 12;24(3):175–188. doi: 10.1093/heapol/czp005

Table 4.

Effects of prenatal care utilization on birth weight adjusted for gestational age

Model Quantile
Mean effect
0.1 0.25 0.5 0.75 0.9
Infants without birth defects
Prenatal care delay in weeks:
    Unadjusted 2.4 (2.4) −0.4 (1.8) 2.0 (2.0) 1.2 (2.5) −0.2 (3.7) 1.0 (1.6)
    Adjusted 3.5 (2.5) 1.5 (2.7) 3.5** (1.5) 2.2 (1.8) 2.8 (2.9) 2.1 (1.6)
Prenatal care visits:
    Unadjusted 7.5 (6.8) 14.4*** (4.5) 9.4** (4.4) 2.7 (7.5) 10.7 (8.8) 11.4*** (4.4)
    Adjusted 15.0** (6.5) 24.9*** (5.4) 8.5** (3.7) 12.2* (6.2) 10.4* (5.8) 17.2*** (4.7)
Inadequate care:
    Unadjusted −79.0 (53.5) −89.1* (47.9) −100.0 (73.0) −133.6*** (49.1) −67.0 (70.5) −104.6*** (38.0)
    Adjusted −134.8** (51.9) −121.4** (58.9) −67.4 (42.5) −114.3* (62.0) −127.4 (80.6) −114.1*** (38.7)
Adequate care:
    Unadjusted −10.0 (39.6) 19.1 (30.6) −4.0 (28.6) −63.6 (46.6) −18.0 (59.5) −14.2 (29.8)
    Adjusted −23.4 (54.5) 35.1 (45.8) −6.2 (29.4) −73.8 (49.4) −54.6 (69.9) −3.7 (30.2)
Infants with birth defects
Prenatal care delay in weeks:
    Unadjusted −2.8 (2.9) −5.0 (3.5) −5.2* (2.7) −5.0** (2.1) −4.4* (2.6) −3.5* (1.8)
    Adjusted −7.0 (5.2) −2.6 (3.8) −2.7 (3.2) −4.4* (2.5) −4.0 (3.8) −3.7* (2.0)
Prenatal care visits:
    Unadjusted −2.9 (6.1) 0.2 (6.1) 7.9 (6.4) 3.3 (8.0) 14.0** (7.0) 5.8 (5.0)
    Adjusted 4.5 (6.7) 0.2 (4.5) 4.1 (6.0) 12.7 (8.0) 11.3 (12.8) 8.9 (5.5)
Inadequate care:
    Unadjusted −35.8 (67.4) −29.4 (65.6) −73.3 (63.3) −85.0 (68.0) −100.0* (55.2) −57.9 (44.5)
    Adjusted −47.4 (83.8) −26.9 (62.2) −16.5 (53.2) 64.1 (43.2) −76.9 (60.8) −63.3 (47.4)
Adequate care:
    Unadjusted 5.0 (52.4) −49.4 (64.4) −20.0 (36.7) 42.5 (40.6) 30.0 (68.3) −23.6 (37.8)
    Adjusted −23.7 (51.9) −77.9* (45.6) −36.2 (46.5) 58.1 (38.5) 11.3 (50.5) −23.8 (38.7)

Notes: This table presents the mean and quantile effects of prenatal care use on birth weight adjusting for gestational age, estimated using ordinary least squares (OLS) and ordinary quantile regression, respectively. The effects were estimated alternatively as unadjusted and adjusted for model covariates.

*, ** and *** indicate significance at P < 0.1, P < 0.05 and P < 0.01, respectively.