Reliability and Validity of Birth Certificate Prepregnancy Weight and Height Among Women Enrolled in Prenatal WIC Program: Florida, 2005

Abstract

To investigate the reliability and validity of weight, height, and body mass index (BMI) from birth certificates with directly measured values from the Women, Infants, and Children (WIC) Program. Florida birth certificate data were linked and compared with first trimester WIC data for women with a live birth during the last quarter of calendar year 2005 (n = 23,314 women). Mean differences for weight, height, and BMI were calculated by subtracting birth certificate values from WIC values. Reliability was estimated by Pearson's correlation. Validity was measured by sensitivity and specificity using WIC data as the reference. Overall mean differences plus or minus standard error (SE) were 1.93 ± 0.04 kg for weight, -1.03 ± 0.03 cm for height, and 1.07 ± 0.02 kg/m(2) for BMI. Pearson's correlation ranged from 0.83 to 0.95, which indicates a strong positive association. Compared with other categories, women in the second weight group (56.7-65.8 kg), the highest height group (≥167.6 cm), or BMI < 18.5 had the greatest mean differences for weight (2.2 ± 0.08 kg), height (-2.4 ± 0.05 cm), and BMI (1.5 ± 0.06), respectively. Mean differences by maternal characteristics were similar, but statistically significant, likely in part from the large sample size. The sensitivity for birth certificate data was 77.3% (±1.42) for underweight (BMI < 18.5) and 76.4% (±0.51) for obesity (BMI ≥ 30). Specificity was 96.8% (±0.12) for underweight and 97.5% (±0.12) for obesity. Birth certificate data had higher underweight prevalence (6 vs. 4%) and lower obesity prevalence (24 vs. 29%), compared with WIC data. Although birth certificate data overestimated underweight and underestimated obesity prevalence, the difference was minimal and has limited impact on the reliability and validity for population-based surveillance and research purposes related to recall or reporting bias.

Validation of Selected Items on the 2003 U.S. Standard Certificate of Live Birth: New York City and Vermont

“…Even items that had large discrepancies between the birth certificate and the medical record, such as hypertension in NYC and PROM in Vermont, had excellent or near-excellent specificity and NPV. Our results for Medicaid coverage are consistent with two previous state-based studies-one conducted in California, 11 which found an overall agreement of 95.8% between birth certificate and women's self-report on a survey; and the other in Iowa, 9 which found a sensitivity of 86.3% and specificity of 91.9% for birth certificates using matched Medicaid claims records as the gold standard. Our sensitivity estimates for Medicaid coverage, however, were generally higher than that found in an NCHS study of eight hospitals in two states, where sensitivity for Medicaid coverage in each hospital ranged from ,50% to .90%.…”

Prenatal Risk Factors for Childhood CKD

“…Nevertheless, birth certificate data seem to be both reliable and valid when used for research purposes, with recall or reporting bias having minimal effect. 24 The BMI data are thought to be missing at random, because entry into the dataset depended on documentation by WA data entry staff using medical chart data, physician report, or maternal recall, and they should not be a source of bias. Moreover, our case definition may underestimate the prevalence of CKD in WA.…”

Pre‐pregnancy body mass index, weight change during pregnancy, and risk of intellectual disability in children

“…1 Limitation in intellectual ability corresponds to an intelligence quotient (IQ) of <70, described as mild (IQ 55-70), moderate (IQ [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55], or severe to profound (IQ of <40). 2 The prevalence of ID in the general population is estimated to be approximately 1%, and among those with ID 85% are characterised as having mild ID.…”