Clinical Estimate Of Gestational Age Research Articles

Racial/Ethnic Disparities in Very Preterm Birth and Preterm Birth Before and During the COVID-19 Pandemic

The coronavirus disease 2019 (COVID-19) pandemic may exacerbate existing racial/ethnic inequities in preterm birth. To assess whether racial/ethnic disparities in very preterm birth (VPTB) and preterm birth (PTB) increased during the first wave of the COVID-19 pandemic in New York City. This cross-sectional study included 8026 Black, Latina, and White women who gave birth during the study period. A difference-in-differences (DID) analysis of Black vs White disparities in VPTB or PTB in a pandemic cohort was compared with a prepandemic cohort by using electronic medical records obtained from 2 hospitals in New York City. Women who delivered from March 28 to July 31, 2020, were considered the pandemic cohort, and women who delivered from March 28 to July 31, 2019, were considered the prepandemic cohort. Reverse transcription-polymerase chain reaction tests for the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were performed using samples obtained via nasopharyngeal swab at the time of admission. Clinical estimates of gestational age were used to calculate VPTB (<32 weeks) and PTB (<37 weeks). Log binomial regression was performed to estimate Black vs White risk differences, pandemic cohort vs prepandemic cohort risk difference, and an interaction term representing the DID estimator. Covariate-adjusted models included age, insurance, prepregnancy body mass index, and parity. Of 3834 women in the pandemic cohort, 492 (12.8%) self-identified as Black, 678 (17.7%) as Latina, 2012 (52.5%) as White, 408 (10.6%) as Asian, and 244 (6.4%) as other or unspecified race/ethnicity, with approximately half the women 25 to 34 years of age. The prepandemic cohort comprised 4192 women with similar sociodemographic characteristics. In the prepandemic cohort, VPTB risk was 4.4% (20 of 451) and PTB risk was 14.4% (65 of 451) among Black infants compared with 0.8% (17 of 2188) VPTB risk and 7.1% (156 of 2188) PTB risk among White infants. In the pandemic cohort, VPTB risk was 4.3% (21 of 491) and PTB risk was 13.2% (65 of 491) among Black infants compared with 0.5% (10 of 1994) VPTB risk and 7.0% (240 of 1994) PTB risk among White infants. The DID estimators indicated that no increase in Black vs White disparities were found (DID estimator for VPTB, 0.1 additional cases per 100 [95% CI, -2.5 to 2.8]; DID estimator for PTB, 1.1 fewer case per 100 [95% CI, -5.8 to 3.6]). The results were comparable in covariate-adjusted models when limiting the population to women who tested negative for SARS-CoV-2. No change was detected in Latina vs White PTB disparities during the pandemic. In this cross-sectional study of women who gave birth in New York City during the COVID-19 pandemic, no evidence was found for increased racial/ethnic disparities in PTB, among women who tested positive or tested negative for SARS-CoV-2.

Committee Opinion No. 688: Management of Suboptimally Dated Pregnancies.

The American College of Obstetricians and Gynecologists considers first-trimester ultrasonography to be the most accurate method to establish or confirm gestational age. Pregnancies without an ultrasonographic examination confirming or revising the estimated due date before 22 0/7 weeks of gestation should be considered suboptimally dated. This document provides guidance for managing pregnancies in which the best clinical estimate of gestational age is suboptimal. There is no role for elective delivery in a woman with a suboptimally dated pregnancy. Although guidelines for indicated late-preterm and early-term deliveries depend on accurate determination of gestational age, women with suboptimally dated pregnancies should be managed according to these same guidelines because of the lack of a superior alternative. The best clinical estimate of gestational age should serve as the basis for decisions regarding antenatal corticosteroid exposure in women with suboptimally dated pregnancies who are at perceived risk of preterm delivery. Amniocentesis for fetal lung maturity is not recommended as a routine component of decision making when considering delivery in a woman with a suboptimally dated pregnancy. Late-term delivery is indicated at 41 weeks of gestation when gestational age is uncertain, using the best clinical estimate of gestational age. Initiation of antepartum fetal surveillance at 39-40 weeks of gestation may be considered for suboptimally dated pregnancies. During the antenatal care of a woman with a suboptimally dated pregnancy, it is reasonable to consider an interval ultrasonographic assessment of fetal weight and gestational age 3-4 weeks after the initial ultrasonographic study.

Committee opinion No. 688 Summary: Management of Suboptimally Dated Pregnancies.

The American College of Obstetricians and Gynecologists considers first-trimester ultrasonography to be the most accurate method to establish or confirm gestational age. Pregnancies without an ultrasonographic examination confirming or revising the estimated due date before 22 0/7 weeks of gestation should be considered suboptimally dated. This document provides guidance for managing pregnancies in which the best clinical estimate of gestational age is suboptimal. There is no role for elective delivery in a woman with a suboptimally dated pregnancy. Although guidelines for indicated late-preterm and early-term deliveries depend on accurate determination of gestational age, women with suboptimally dated pregnancies should be managed according to these same guidelines because of the lack of a superior alternative. The best clinical estimate of gestational age should serve as the basis for decisions regarding antenatal corticosteroid exposure in women with suboptimally dated pregnancies who are at perceived risk of preterm delivery. Amniocentesis for fetal lung maturity is not recommended as a routine component of decision making when considering delivery in a woman with a suboptimally dated pregnancy. Late-term delivery is indicated at 41 weeks of gestation when gestational age is uncertain, using the best clinical estimate of gestational age. Initiation of antepartum fetal surveillance at 39-40 weeks of gestation may be considered for suboptimally dated pregnancies. During the antenatal care of a woman with a suboptimally dated pregnancy, it is reasonable to consider an interval ultrasonographic assessment of fetal weight and gestational age 3-4 weeks after the initial ultrasonographic study.

Association Between Preterm Delivery and Pre-pregnancy Body Mass (BMI), Exercise and Sleep During Pregnancy Among Working Women in Southern California

Little is known about modifiable lifestyle factors beyond quitting smoking that could prevent preterm delivery (PTD, <37 weeks gestation). We examined the individual and joint associations of pre-pregnancy BMI, second trimester exercise and sleep on PTD. We conducted a nested, population-based case-control study interviewing postpartum 344 cases delivering at <37 weeks, as identified by clinical estimate of gestational age from prenatal screening records, and 698 term controls, excluding term low birthweight. Eligible women participated in California's statewide Prenatal Screening Program, worked during pregnancy, and delivered a singleton birth in Southern California in 2002-2003. Modeled separately, moderate (odds ratio [OR] = 0.90; 95% confidence interval [CI] = 0.84-0.96--per hour/week) and vigorous (OR = 0.67; 95% CI = 0.46-0.98 for yes vs. no) exercise during the second trimester were associated with a reduced odds of PTD, and sleep duration was not (OR = 1.09, 95% CI = 0.80-1.48 for <7 h; OR = 0.88, 95% CI = 0.57-1.48 for >8 h vs. 7-8 h). When sleep and exercise variables were modeled together along with pre-pregnancy BMI, only moderate exercise (OR = 0.91; 95% CI 0.85-0.98) continued to be associated with reduced odds of PTD. The benefits of moderate exercise appeared strongest for women with BMI greater than 24 kg/m(2) (OR = 0.85; 95% CI = 0.79-0.93) and weakened with decreasing BMI. No other interactions were found. Moderate exercise is associated with reduced PTD, particularly for women with BMI above the normal range. The results are of public health relevance given that these risk factors are potentially modifiable both pre-conceptionally and during pregnancy and rates of PTD are still high in the United States.

Challenges in defining and classifying the preterm birth syndrome

In 2009, the Global Alliance to Prevent Prematurity and Stillbirth Conference charged the authors to propose a new comprehensive, consistent, and uniform classification system for preterm birth. This first article reviews issues related to measurement of gestational age, clinical vs etiologic phenotypes, inclusion vs exclusion of multifetal and stillborn infants, and separation vs combination of pathways to preterm birth. The second article proposes answers to the questions raised here, and the third demonstrates how the proposed system might work in practice.

The use of covariates to identify records with implausible gestational ages using the birthweight distribution

The objective of this study was to evaluate the usefulness of covariates in identifying birth records with implausible values of gestational age. Birthweight distributions for births with early reported gestational ages are markedly bimodal, suggesting a mixture of two distributions. Most births form a normal-shaped left-hand (primary) distribution and a smaller number form the right-hand (secondary) distribution. The births in the secondary distribution are thought to have gestational age mistakenly reported. Prior work has found that births in the secondary distribution are at higher risk of poor outcomes than those in the primary distribution. Using 2002 US Natality data for gestational ages 26-35 weeks, we fit normal mixture models to birthweight with and without covariates (maternal race, education, parity, age, region of the country, prenatal care initiation) by reported gestational age. Additional models were stratified by infant sex. This approach allowed for the relationship between the covariates and birthweight to differ between the components. Mixture models fit reasonably well for reported gestational ages <33 weeks, but not for later weeks. Counter to the hypothesis, results were similar for models with and without covariates or stratification or both, although stratified models without covariates predicted slightly more girls and slightly fewer boys in the secondary distribution than did the corresponding unstratified models. For reported gestational ages <33 weeks, predictions from the four sets of models were highly correlated and predictions were similar for subgroups defined by the clinical estimates of gestational age and other covariates. For births with reported gestational ages of 29 or more weeks, the proportion in the secondary distribution exceeded 30%, although this varied by maternal characteristics. The use of covariates and stratification complicated model fitting without materially improving identification of implausible gestational age values, supporting inferences from prior studies using data 'cleaned' without consideration of maternal or infant characteristics.

The association between pre-pregnancy BMI and preterm delivery in a diverse southern California population of working women.

Whereas preterm birth has consistently been associated with low maternal pre-pregnancy weight, the relationship with high pre-pregnancy weight has been inconsistent. We quantified the pre-pregnancy BMI—preterm delivery (PTD) relationship using traditional BMI categories (underweight, normal weight, overweight and obese) as well as continuous BMI. Eligible women participated in California’s statewide prenatal screening program, worked during pregnancy, and delivered a live singleton birth in Southern California in 2002–2003. The final analytic sample included 354 cases delivering at <37 weeks, as identified by clinical estimate of gestational age from screening records, and 710 term normal-birthweight controls. Multivariable logistic regression models using categorical BMI levels and continuous BMI were compared. In categorical analyses, PTD was significantly associated with pre-pregnancy underweight only. Nonparametric local regression revealed a V-shaped relationship between continuous BMI and PTD, with minimum risk at the high end of normal, around 24 kg/m2. The odds ratio (OR) for PTD associated with low BMI within the normal range (19 kg/m2) was 2.84 (95%CI = 1.61–5.01); ORs for higher BMI in the overweight (29 kg/m2) and obese (34 kg/m2) ranges were 1.42 (95%CI = 1.10–1.84) and 2.01 (95% CI = 1.20–3.39) respectively, relative to 24 kg/m2). BMI categories obscured the preterm delivery risk associated with low-normal, overweight, and obese BMI. We found that higher BMI up to around 24 kg/m2 is increasingly protective of preterm delivery, beyond which a higher body mass index becomes detrimental. Current NHLBI/WHO BMI categories may be inadequate for identifying women at higher risk for PTD.

Variation between Last-Menstrual-Period and Clinical Estimates of Gestational Age in Vital Records

An accurate assessment of gestational age is vital to population-based research and surveillance in maternal and infant health. However, the quality of gestational age measurements derived from birth certificates has been in question. Using the 2002 US public-use natality file, the authors examined the agreement between estimates of gestational age based on the last menstrual period (LMP) and clinical estimates in vital records across durations of gestation and US states and explored reasons for disagreement. Agreement between the LMP and the clinical estimate of gestational age varied substantially across gestations and among states. Preterm births were more likely than term births to have disagreement between the two estimates. Maternal age, maternal education, initiation of prenatal care, order of livebirth, and use of ultrasound had significant independent effects on the disagreement between the two measures, regardless of gestational age, but these factors made little difference in the magnitude of gestational age group differences. Information available on birth certificates was not sufficient to understand this disparity. The lowest agreement between the LMP and the clinical estimate was observed among preterm infants born at 28-36 weeks' gestation, who accounted for more than 90% of total preterm births. This finding deserves particular attention and further investigation.

Menstrual versus clinical estimate of gestational age dating in the United States: temporal trends and variability in indices of perinatal outcomes

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 (>or=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.

Comparative accuracy of clinical estimate versus menstrual gestational age in computerized birth certificates

Objective. This study compares gestational age data obtained by clinical estimate with data calculated from the date of the last menstrual period (LMP) as recorded on birth certificates. Methods. The authors analyzed 476,034 computerized birth records from three overlap years, that is, those that contained both menstrual and clinical estimates of gestational age, concentrating on cases within the biologically plausible range of 20-44 weeks. Results. The overall exact concordance between the two measurements was 46%. For +1 week it was 78%, and for +2 weeks it was 87%. Incidence of prematurity was 16% with menstrual gestational age, while it was 12% with clinical estimate. About 47% of the LMP-based preterm births were classified as term by clinical estimate. Eighty-three percent of clinical estimate-based preterms were also preterms by LMP-based gestation. Birthweight frequency distribution curves for LMP-based gestational age are bimodal, indicating probable miscoding of term births. An apparent over-representation of births coded as exactly 40 weeks by clinical estimate suggests rounding off near term for this method. Conclusion. Agreement between menstrual and clinical estimates of gestational age occurs most often close to term, with significant disagreement in preterm and postterm births. Use of different methods of determining gestation in different years or geographic populations will result in artifactual differences in important indicators such as prematurity rate.

Birth size of Australian Aboriginal babies

(i) To describe birth size of Aboriginal babies by sex, gestational age, and Aboriginality; (ii) to analyse the results with reference to standards of ponderal index and birthweight for gestational age. 570 liveborn singletons routinely delivered at Royal Darwin Hospital between January 1987 and March 1991, and recorded in the Delivery Suite Register as being born to an Aboriginal mother. Weight, length and head circumference at birth. The mean birthweight was 3098 g (standard deviation, 601 g), peak gestational age was 39 weeks, 13% were low birthweight and 7% were preterm. Preterm rates did not differ significantly for sex and Aboriginality. Babies without a non-Aboriginal ancestor had a lower mean birthweight and at term, were significantly smaller than babies with a non-Aboriginal ancestor as assessed by mean birthweight, length, head circumference and ponderal index. More than a quarter of babies (27%) without a non-Aboriginal ancestor were below the 10th percentile of birthweight for gestational age, compared with 14.2% of babies with a non-Aboriginal ancestor. On the basis of postnatal clinical estimates of gestational age, Aboriginal babies have a preterm rate of 7% and Aboriginal babies without a non-Aboriginal ancestor are smaller in size at birth than babies with a non-Aboriginal ancestor.

Effects of race on the validity of clinical estimates of gestational age

that accuracy was limited in heelstick blood whether one evaluated the percentage of difference between the means or the least squares regression for all the meters tested. The use of cord blood appeared to be associated with greater accuracy than the use of capillary blood obtained by heelstick in the analyses. The reason for the poor correlations with capillary samples and the high variability in the values of blood glucose concentrations is unclear. Furthermore, there was no relationship between accuracy and reliability of the glucose reflectance meter. The Diascan S meter, which seemed to have accuracy closest to that of the YSI analyzer, was clearly not the most reliable in comparison with the YSI analyzer. On the other hand, the One Touch meter, which had the best reliability among the four glucose reflectance meters tested, was the least accurate. We conclude that, contrary to the manufacturers' claims, glucose reflectance meters should probably not be used for evaluation of capillary blood glucose concentrations in the high-risk neonate. We appreciate the statistical analyses performed by Dr. Stanley Sady.

Estimation of gestational age by electrographic, clinical, and anatomic criteria

Current methods for estimating gestational age utilizing clinical parameters can be inaccurate in the very premature neonate. Neuropathologic studies have been used to verify these clinical estimates of gestational age. Estimates of maturity using neonatal electroencephalography have documented the evolution of regional and hemispheric electrical patterns at different gestational ages; however, electroencephalographic studies have not been compared with both anatomic brain studies and clinical examination criteria. Therefore, we studied 25 neonates with at least one electroencephalographic study prior to death and subsequent neuropathologic examination. Twenty-three estimates (92%) of gestational age in weeks, which were based on specific electrical patterns, agreed with sulcal-gyral development (e.g., the delineation of inferior frontal, superior temporal, calcarine sulci, and cytoarchitecture in various brain regions). Clinical (Ballard score) criteria and anatomic estimations of gestational age agreed in 18 of 24 patients (74%). Electroencephalographic estimates were significantly better than clinical estimates ( p < .05) for sick neonates who were ≤ 30 weeks gestational age.

The effect of ventricular dilatation upon biometry of the fetal head.

The ultrasonograms of 15 patients with moderate to marked fetal hydrocephalus were evaluated retrospectively in an attempt to determine the effect of ventricular dilatation upon biometry of the fetal head in the latter half of pregnancy. In 13 of the 15 cases the age based upon biometry of the fetal head was within one week of the clinical estimate of gestational age based upon the last menstrual period. As accurate head measurements may be useful even in cases of hydrocephalus, these measurements should not be dismissed as being invalid particularly when commensurate with a clinical estimate of gestational age.