Demographic characteristics by response status and response time.

<p>Note: total n is not the same for VFC status and mean daily number of patients due to item specific non-response.</p><p>*Means and standard deviations are given for continuous variables, counts and percents for categorical variables.</p><p>**P-Values reported in this column are group tests. For example, the P-Value reported for type of practice compares the model including practice type variables to the one not including practice type variables by likelihood ratio tests.</p><p>***P<0.05. Individually significant variables marked with *** were compared to a reference category by Fisher exact test.</p

Number of responses and response rate by week and timing of follow-up.

<p>Number of responses and response rate by week and timing of follow-up.</p

Survey estimates by timing of response.

<p>Note: n varies by variable due to item specific non-response.</p><p>*P-values reported are Fisher exact tests between timing of response and survey answers.</p

Logistic Regression: Association between survey estimates with geographic and demographic variables.

<p>Note: model with Easy adherence as the dependent variable was not significant P>0.05.</p><p>*Per ten mile increase.</p

Logistic Regression: Association between response and timing of response with geographic and demographic variables.

<p>Note: the model with late response as the dependent variable is not significant P>0.05.</p><p>*Per ten mile increase.</p><p>**P<0.05.</p

Determining gestational age and preterm birth in rural Guatemala: A comparison of methods

<div><p>Background</p><p>Preterm birth is the leading cause of death among children <5 years of age. Accurate determination of prematurity is necessary to provide appropriate neonatal care and guide preventive measures. To estimate the most accurate method to identify infants at risk for adverse outcomes, we assessed the validity of two widely available methods—last menstrual period (LMP) and the New Ballard (NB) neonatal assessment—against ultrasound in determining gestational age and preterm birth in highland Guatemala.</p><p>Methods</p><p>Pregnant women (n = 188) were recruited with a gestational age <20 weeks and followed until delivery. Ultrasound was performed by trained physicians and LMP was collected during recruitment. NB was performed on infants within 96 hours of birth by trained study nurses. LMP and NB accuracy at determining gestational age and identifying prematurity was assessed by comparing them to ultrasound.</p><p>Results</p><p>By ultrasound, infant mean gestational age at birth was 38.3 weeks (SD = 1.6) with 16% born at less than 37 gestation. LMP was more accurate than NB (mean difference of +0.13 weeks for LMP and +0.61 weeks for NB). However, LMP and NB estimates had low agreement with ultrasound-determined gestational age (Lin’s concordance<0.48 for both methods) and preterm birth (κ<0.29 for both methods). By LMP, 18% were judged premature compared with 6% by NB. LMP underestimated gestational age among women presenting later to prenatal care (0.18 weeks for each additional week). Gestational age for preterm infants was overestimated by nearly one week using LMP and nearly two weeks using NB. New Ballard neuromuscular measurements were more predictive of preterm birth than those measuring physical criteria.</p><p>Conclusion</p><p>In an indigenous population in highland Guatemala, LMP overestimated prematurity by 2% and NB underestimated prematurity by 10% compared with ultrasound estimates. New, simple and accurate methods are needed to identify preterm birth in resource-limited settings worldwide.</p></div

Sociodemographic characteristics of study participants.

<p>Sociodemographic characteristics of study participants.</p

Gestational age distributions by NB, LMP and ultrasound.

<p>The vertical line indicates 37 weeks, the threshold between term and preterm births (y-axis is the kernel density of the gestational age distribution for each method).</p

Difference between ultrasound and LMP or New Ballard-determined gestational age by maternal and infant characteristics.

<p>Difference between ultrasound and LMP or New Ballard-determined gestational age by maternal and infant characteristics.</p

Performance of LMP and Ballard to determine gestational age at birth compared to ultrasound.

<p>Performance of LMP and Ballard to determine gestational age at birth compared to ultrasound.</p