Inadequate prenatal care and its association with adverse pregnancy outcomes: A comparison of indices

Maureen I Heaman¹^,2^,5 , Christine V Newburn-Cook³ , Chris G Green⁴^,5 , Lawrence J Elliott⁵^,6 and Michael E Helewa²

¹Faculty of Nursing, Room 217 Helen Glass Centre for Nursing, University of Manitoba, Winnipeg, Manitoba, R3T 2N2 Canada

²Department of Obstetrics, Gynecology, and Reproductive Sciences, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada

³Faculty of Nursing, University of Alberta, Edmonton, Alberta, Canada

⁴Manitoba Agriculture, Food and Rural Initiatives, Winnipeg, Manitoba, Canada

⁵Department of Community Health Sciences, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada

⁶Department of Medical Microbiology, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada

author email corresponding author email

BMC Pregnancy and Childbirth 2008, 8:15doi:10.1186/1471-2393-8-15


Published:	1 May 2008

Abstract

Background

The objectives of this study were to determine rates of prenatal care utilization in Winnipeg, Manitoba, Canada from 1991 to 2000; to compare two indices of prenatal care utilization in identifying the proportion of the population receiving inadequate prenatal care; to determine the association between inadequate prenatal care and adverse pregnancy outcomes (preterm birth, low birth weight [LBW], and small-for-gestational age [SGA]), using each of the indices; and, to assess whether or not, and to what extent, gestational age modifies this association.

Methods

We conducted a population-based study of women having a hospital-based singleton live birth from 1991 to 2000 (N = 80,989). Data sources consisted of a linked mother-baby database and a physician claims file maintained by Manitoba Health. Rates of inadequate prenatal care were calculated using two indices, the R-GINDEX and the APNCU. Logistic regression analysis was used to determine the association between inadequate prenatal care and adverse pregnancy outcomes. Stratified analysis was then used to determine whether the association between inadequate prenatal care and LBW or SGA differed by gestational age.

Results

Rates of inadequate/no prenatal care ranged from 8.3% using APNCU to 8.9% using R-GINDEX. The association between inadequate prenatal care and preterm birth and LBW varied depending on the index used, with adjusted odds ratios (AOR) ranging from 1.0 to 1.3. In contrast, both indices revealed the same strength of association of inadequate prenatal care with SGA (AOR 1.4). Both indices demonstrated heterogeneity (non-uniformity) across gestational age strata, indicating the presence of effect modification by gestational age.

Conclusion

Selection of a prenatal care utilization index requires careful consideration of its methodological underpinnings and limitations. The two indices compared in this study revealed different patterns of utilization of prenatal care, and should not be used interchangeably. Use of these indices to study the association between utilization of prenatal care and pregnancy outcomes affected by the duration of pregnancy should be approached cautiously.