Comparison of gestational age at birth based on last menstrual period and ultrasound during the first trimester

Abstract

Reported last menstrual period (LMP) is commonly used to estimate gestational age (GA) but may be unreliable. Ultrasound in the first trimester is generally considered a highly accurate method of pregnancy dating. The authors compared first trimester report of LMP and first trimester ultrasound for estimating GA at birth and examined whether disagreement between estimates varied by maternal and infant characteristics. Analyses included 1867 singleton livebirths to women enrolled in a prospective pregnancy cohort. The authors computed the difference between LMP and ultrasound GA estimates (GA difference) and examined the proportion of births within categories of GA difference stratified by maternal and infant characteristics. The proportion of births classified as preterm, term and post-term by pregnancy dating methods was also examined. LMP-based estimates were 0.8 days (standard deviation = 8.0, median = 0) longer on average than ultrasound estimates. LMP classified more births as post-term than ultrasound (4.0% vs. 0.7%). GA difference was greater among young women, non-Hispanic Black and Hispanic women, women of non-optimal body weight and mothers of low-birthweight infants. Results indicate first trimester report of LMP reasonably approximates gestational age obtained from first trimester ultrasound, but the degree of discrepancy between estimates varies by important maternal characteristics.

Risk Factors for Maternal Injuries in a Population-Based Sample of Pregnant Women

“…We hypothesize that this may be owing to younger women being more likely to have unintended pregnancies. 16,17 Therefore, the two studies may be measuring a similar factor, although they were not strongly correlated (r = 0.30, p = <0.0001). This same relationship may exist between living in or near poverty and unintended pregnancy (r = 0.34, p = < 0.0001), potentially reducing the effect of poverty.…”

The Fault in Our Moons- The Effect of Festivals and Public Holidays in the Introduction of Error in Recalled LMP Dates by Pregnant Subjects Undergoing First Trimester Scan

“…non-Hispanic Black, Hispanic women and women of non-optimal body weight. (3) No studies exist showing inaccuracies in scan derived gestational ages in Asian populations.…”

Determinação da idade gestacional com base em informações do estudo Nascer no Brasil

“…In 2011, this information came to be collected in a disaggregated way, according to weeks of gestation, with the main calculation method being the date of the last menstrual period (LMP) 2 , and making possible the recording of gestational age information based on other assessment methods (physical examination or ultrasound imaging) 2 . However, these methods have different levels of validity 3,4,5,6 , making the assessment of gestational age in the country more difficult.…”

“…In Brazil, a high proportion of the population has low schooling -a feature associated to worse quality of information about LMP 5,6 . In a study carried out with users of the Brazilian Unified National Health System (SUS) in two cities, it was seen that LMP-calculated gestational age compared to early-US-estimated gestational age tends to overestimate both postmaturity and prematurity proportions, reaching 10.3% and 17.7 % of births, respectively 4 .…”