Abstract:
Objectives We examined gestational age (GA) estimates
for live and still births, and prematurity rates based on last
menstrual period (LMP) compared with ultrasonography
(USG) among pregnant women at seven sites in six low-
resource countries.
Design Prospective cohort study
Setting and participants This study included data
from the Global Network’s population-based Maternal
and Newborn Health Registry which follows pregnant
women in six low-income and middle-income countries
(Democratic Republic of the Congo, Guatemala, India,
Kenya, Pakistan and Zambia). Participants in this analysis
were 42 803 women, including their 43 230 babies, who
registered for the study in their first trimester based on GA
estimated either by LMP or USG and had a live or stillbirth
with an estimated GA of 20–42 weeks.
Outcome measures GA was estimated in weeks and
days based on LMP and/or USG. Prematurity was defined
as GA of 20 weeks+0 days through 36 weeks+6 days,
calculated by both USG and LMP.
Results Overall, average GA varied ≤1 week between LMP
and USG. Mean GA for live births by LMP was lower than
by USG (adjusted mean difference (95% CI) = −0.23 (–0.29
to –0.17) weeks). Among stillbirths, a higher GA was
estimated by LMP than USG (adjusted mean difference
(95% CI)= 0.42 (0.11 to 0.72) weeks). Preterm birth rates
for live births were significantly higher when dated by LMP
(adjusted rate difference (95% CI)= 4.20 (3.56 to 4.85)).
There was no significant difference in preterm birth rates
for stillbirths.
Conclusion The small differences in GA for LMP versus
USG in the Guatemalan and Indian sites suggest that LMP
may be a useful alternative to USG for GA dating during the
first trimester until availability of USG improves in those
areas. Further research is needed to assess LMP for first-
trimester GA dating in other regions with limited access
to USG.
