Conflicts of interest: the authors have declared no conflicts of interest.
Menstrual versus clinical estimate of gestational age dating in the United States: temporal trends and variability in indices of perinatal outcomes
Article first published online: 30 AUG 2007
Paediatric and Perinatal Epidemiology
Special Issue: Addressing Gestational Age Measurement Using Birth Certificate Data
Volume 21, Issue Supplement s2, pages 22–30, September 2007
How to Cite
Ananth, C. V. (2007), Menstrual versus clinical estimate of gestational age dating in the United States: temporal trends and variability in indices of perinatal outcomes. Paediatric and Perinatal Epidemiology, 21: 22–30. doi: 10.1111/j.1365-3016.2007.00858.x
- Issue published online: 30 AUG 2007
- Article first published online: 30 AUG 2007
- birth records;
- gestational age;
- time trends;
Accurate estimation of gestational age early in pregnancy is paramount for obstetric care decisions and for determining fetal growth and other conditions that may necessitate timing the iatrogenic intervention or delivery. We sought to examine temporal changes in the distributions of two measures of gestational age, namely, those based on menstrual dating and a clinical estimate. We further sought to evaluate relative comparisons and variability in indices of perinatal outcomes. We utilised the Natality data files in the US, 1990–2002 comprising women that delivered a singleton livebirth between 22 and 44 weeks gestation (n = 42 689 603).
Changes were shown in the distributions of gestational age based on menstrual vs. clinical estimate between 1990 and 2002, as well as changes in the proportions of preterm (<37, <32 and <28 weeks) and post-term (≥42 weeks) birth, and small- (SGA; <10th percentile) and large-for-gestational-age (LGA; birthweight >90th percentile) births. While the absolute rates of preterm birth <37 weeks, SGA and LGA births were lower based on the clinical estimate of gestational age relative to that based on menstrual dating, the increases in preterm birth rate between 1990 and 2002 were fairly similar between the two measures of gestational dating. However, the decline in post-term births was larger, based on the clinical estimate (−73.8%), than on the menstrual estimate (−36.6%) between 1990 and 2002. While the clinical estimate of gestational age appears to provide a reasonably good approximation to the menstrual estimate, disregarding the clinical estimate of gestational age may ignore the advantages of gestational age assessment in modern obstetrics.