Comparison of gestational dating methods and implications for exposure–outcome associations: an example with PM_2.5and preterm birth

Abstract

Different results from analyses restricted to births with both CE and LMP are most likely due to differences in dating methods rather than selection issues. Results are sensitive to choice of gestational age estimation, though degree of sensitivity can vary by exposure timing. When both outcome and exposure depend on estimate of gestational age, awareness of nuances in the method used for estimation is critical.

Impact of eating disorders on obstetric outcomes in a large clinical sample: A comparison with the HUNT study

“…In the sensitivity analyses restricting to ultrasound dated pregnancies, we found higher odds of having an offspring who were SGA compared to our main analysis. Generally, using LMP to estimate gestational age based is considered less accurate compared to ultrasound dating as it tends to classify more deliveries as preterm (Rappazzo, Lobdell, Messer, Poole, & Daniels, 2017;Tunon et al, 1996). However, our sensitivity analyses may be explained by factors that reduce fetal size which may increase the risk of preterm delivery when gestational age is based on ultrasound measurements (Henriksen, Wilcox, Hedegaard, & Secher, 1995).…”

“…Generally, using LMP to estimate gestational age based is considered less accurate compared to ultrasound dating as it tends to classify more deliveries as preterm (Rappazzo, Lobdell, Messer, Poole, & Daniels, 2017;Tunon et al, 1996). Generally, using LMP to estimate gestational age based is considered less accurate compared to ultrasound dating as it tends to classify more deliveries as preterm (Rappazzo, Lobdell, Messer, Poole, & Daniels, 2017;Tunon et al, 1996).…”

Normotensive preterm delivery and maternal cardiovascular risk factor trajectories across the life course: The HUNT Study, Norway

“…We would expect error introduced by using last menstrual period to bias estimates towards the null, which could explain, in part, our null findings, especially for older women who did not have ultrasound dating as an option for their first pregnancy. As last menstrual period tends to classify more deliveries as preterm, 28 we conducted sensitivity analyses excluding deliveries that were unusually large for their gestational age and found no differences in results. Another potential source of misclassification in this study was antihypertensive medication use, which we accounted for using the recommended 12,13 approach of adding constants to observed blood pressure measurements for users.…”

Impacts of gestational age uncertainty in estimating associations between preterm birth and ambient air pollution

“…Uncertainty in GA can contribute to both outcome misclassification and exposure measurement error when timing of exposure during gestation is important. A previous study of PM 2.5 and PTB by Rappazzo et al 27 found that substantially more births were classified as PTB using LMP estimates. This is consistent with our data.…”

“…Few studies have evaluated effects of uncertainty in GA estimates when examining associations with ambient air pollutant exposure or consider the use of different GA estimates as a sensitivity analysis. Recently, Rappazzo et al 27 found that results can be sensitive to using clinical or LMP GA estimates in an analysis of fine particulate matter and PTB in New Jersey, Pennsylvania, and Ohio, United States. In this study, we evaluated the impact of GA definitions on air pollution risk associations using birth certificates in Atlanta, Georgia, between 2002 and 2006.…”