Maternal and fetal characteristics affect discrepancies between pregnancy-dating methods: a population-based cross-sectional register study

The impact of obesity on first-trimester pregnancy dating using ultrasound: a retrospective cohort study

OBJECTIVES

Obese women are known to have alterations in their menstrual cycles leading to ovulatory dysfunction. The purpose of this study is to evaluate the relationship between body mass index (BMI) and early pregnancy ultrasound dating and determine the frequency of redating.

METHODS

We performed a retrospective cohort study of women who underwent a first trimester dating ultrasound at The University of Oklahoma Health Sciences Center from January 2019 to June 2020. The estimated date of delivery (EDD) calculated from the ultrasound was compared to the EDD calculated from the LMP. A discrepancy of greater than 5 days prior to 9 weeks or greater than 7 days between 9 and 13 weeks prompted redating of the pregnancy.

RESULTS

2639 women met inclusion criteria, with BMI ≥ 30 kg/m2 present in 39% of participants. Obese women had higher rates of pregnancy redating compared to non-obese women-adjusted risk ratio [aRR] 1.23 (95% confidence interval [CI] 1.07-1.41, p = 0.003). Class III obese women were more likely than any other BMI class to have their pregnancies redated by ultrasound-aRR 1.46 (95% CI 1.18-1.80, p < 0.001). Analyses adjusted for age, race, and parity showed that for each unit increase in BMI over 30 kg/m2, women had a 2% increased risk of being redated (p < 0.001). Mean EDD by ultrasound minus mean EDD by LMP was -0.98, -2.70, -2.43, and -3.35 (p < 0.001) for non-obese, class I, class II, and class III obese women, respectively. 22% of non-obese women were redated compared to 27.3% of obese women (p = 0.002) and 31.2% of class III obese women (p = 0.001).

CONCLUSIONS

Obese women have higher rates of pregnancy redating compared to normal weight women, with class III obese women having the highest rates of all groups studied. Accurate pregnancy dating is important to decrease unnecessary interventions due to false diagnoses of fetal growth restriction or macrosomia.

Pregnancy planning and neonatal outcome - a retrospective cohort study

BACKGROUND

Unplanned pregnancy is common, and although some research indicates adverse outcomes for the neonate, such as death, low birth weight, and preterm birth, results are inconsistent. The purpose of the present study was to investigate associated neonatal outcomes of an unplanned pregnancy in a Swedish setting.

METHODS

We conducted a retrospective cohort study in which data from 2953 women were retrieved from the Swedish Pregnancy Planning Study, covering ten Swedish counties from September 2012 through July 2013. Pregnancy intention was measured using the London Measurement of Unplanned Pregnancy. Women with unplanned pregnancies and pregnancies of ambivalent intention were combined and referred to as unplanned. Data on neonatal outcomes: small for gestational age, low birth weight, preterm birth, Apgar score < 7 at 5 min, and severe adverse neonatal outcome defined as death or need for resuscitation at birth, were retrieved from the Swedish Medical Birth Register.

RESULTS

The prevalence of unplanned pregnancies was 30.4%. Compared with women who had planned pregnancies, those with unplanned pregnancies were more likely to give birth to neonates small for gestational age: 3.6% vs. 1.7% (aOR 2.1, 95% CI 1.2-3.7). There were no significant differences in preterm birth, Apgar score < 7 at 5 min, or severe adverse neonatal outcome.

CONCLUSIONS

In a Swedish setting, an unplanned pregnancy might increase the risk for birth of an infant small for gestational age.

The importance of fetal autopsy: An institutional review and development of best practices for reporting size and estimating gestational age at demise

OBJECTIVES

Fetal and neonatal autopsy offers critical insight into disease processes and clinical decision-making in reproductive medicine. Elucidating the cause of death and gaining a deeper understanding of the entities leading to fetal demise aids in anticipatory guidance for physicians and patients. Accurate assessment of growth and dating of fetuses is an important aspect of classifying pathology in the fetal and neonatal population. This study aims to optimize the autopsy approach to sizing and dating discrepancies, in addition to exploring the current trends in causes of stillbirth, with respect to placental, fetal/neonatal, and maternal factors, and rates of cases that remain undetermined after autopsy.

METHODS

A single-institution retrospective review of autopsy reports from mid-2008 through 2021 revealed 243 complete perinatal autopsy examinations.

RESULTS

Placental cause of demise was identified in 46% of cases. Cause of demise was undetermined in 22% of cases. Evaluation of a subset of cases exposed minimal to no reporting of size and/or dating discrepancies in almost half of cases with undetermined cause of death.

CONCLUSIONS

"Best practice" suggestions for sizing and dating fetuses/neonates in the postmortem period have been developed to aid in delivering clear, consistent reports. Because fetal and neonatal autopsy is an invaluable tool for understanding the factors that contribute to stillbirth, it is important to use appropriate sizing and dating methods and consistent language to deliver proper patient education and clinical guidance.

Gestational age at term delivery and children's neurocognitive development

BACKGROUND

Preterm birth is associated with lower neurocognitive performance. However, whether children's neurodevelopment improves with longer gestations within the full-term range (37-41 weeks) is unclear. Given the high rate of obstetric intervention in the USA, it is critical to determine whether long-term outcomes differ for children delivered at each week of term.

METHODS

This secondary analysis included 39 199 live-born singleton children of women who were admitted to the hospital in spontaneous labour from the US Collaborative Perinatal Project (1959-76). At each week of term gestation, we evaluated development at 8 months using the Bayley Scales of Infant Development, 4 years using the Stanford-Binet IQ (SBIQ) domains and 7 years using the Wechsler Intelligence Scales for Children (WISC) and Wide-Range Achievement Tests (WRAT).

RESULTS

Children's neurocognitive performance improved with each week of gestation from 37 weeks, peaking at 40 or 41 weeks. Relative to those delivered at 40 weeks, children had lower neurocognitive scores at 37 and 38 weeks for all assessments except SBIQ and WISC Performance IQ. Children delivered at 39 weeks had lower Bayley Mental (β = -1.18; confidence interval -1.77, -0.58) and Psychomotor (β = -1.18; confidence interval -1.90, -0.46) scores. Results were similar for within-family analyses comparing siblings, with the addition of lower WRAT scores at 39 weeks.

CONCLUSIONS

The improvement in development scores across assessment periods indicates that each week up to 40 or 41 weeks of gestation is important for short- and long-term cognitive development, suggesting 40-41 weeks may be the ideal delivery window for optimal neurodevelopmental outcomes.

Luteinizing Hormone Surge More Accurately Correlates With Ultrasound Dating of Early Pregnancy Compared to the Last Menstrual Period

OBJECTIVES

To compare the use of the luteinizing hormone (LH) surge versus the last menstrual period (LMP) for the accuracy of pregnancy dating in fertile women with a diagnosis of recurrent early pregnancy loss (REPL).

METHODS

This was an observational cohort study using prospectively collected data at 2 academic REPL programs between 2005 and 2018. Women with a history of REPL and at least 1 subsequent live birth after the evaluation were included. All patients conceived by intercourse timed to the LH surge. Transvaginal ultrasound was examinations were performed 2 weeks after missed menses. The gestational age (GA) was calculated by the LH surge (GA_LH ), LMP (GA_LMP ), and first crown-rump length (CRL) that measured 5 mm or greater (GA_CRL ). A secondary analysis compared GA based on the first measurable CRL of less than 5 mm versus GA based on the first CRL of 5 mm or greater. The GA_LH and GA_LMP were compared to determine which measure showed greater concordance with the CRL. The mean absolute difference in days between the GA_CRL versus GA_LH and GA_CRL versus GA_LMP was determined.

RESULTS

A total of 115 women with 118 subsequent pregnancies resulting in live birth were included, with a mean age at delivery of 35.5 years and a mean of 3.6 prior pregnancy losses. The GA_LH showed a stronger correlation with the CRL (0.77) than the GA_LMP (0.63; P = .002). The GA_LH was more similar to the GA_CRL than the GA_LMP , with a mean absolute difference of 2.0 versus 3.1 days (P < .0001).

CONCLUSIONS

When known, the LH surge appears to be more accurate than the LMP and should be used preferentially for dating of early pregnancy.

Maternal asthma and early fetal growth, the MAESTRO study

BACKGROUND

Several maternal conditions can affect fetal growth, and asthma during pregnancy is known to be associated with lower birth weight and shorter gestational age.

OBJECTIVE

In a new Swedish cohort study on maternal asthma exposure and stress during pregnancy (MAESTRO), we have assessed if there is evidence of early fetal growth restriction in asthmatic women or if a growth restriction might come later during pregnancy.

METHODS

We recruited women from eight antenatal clinics in Stockholm, Sweden. Questionnaires on background factors, asthma status and stress were assessed during pregnancy. The participants were asked to consent to collection of medical records including ultrasound measures during pregnancy, and linkage to national health registers. In women with and without asthma, we studied reduced or increased growth by comparing the second-trimester ultrasound with first-trimester estimation. We defined reduced growth as estimated days below the 10th percentile and increased growth as days above the 90th percentile. At birth, the weight and length of the newborn and the gestational age was compared between women with and without asthma.

RESULTS

We enrolled 1693 participants in early pregnancy and collected data on deliveries and ultrasound scans in 1580 pregnancies, of which 18% of the mothers had asthma. No statistically significant reduced or increased growth between different measurement points were found when women with and without asthma were compared; adjusted odds ratios for reduced growth between first and second trimester 1.11 95% CI (0.63-1.95) and increased growth 1.09 95% CI (0.68-1.77).

CONCLUSION AND CLINICAL RELEVANCE

In conclusion, we could not find evidence supporting an influence of maternal asthma on early fetal growth in the present cohort: Although the relatively small sample size, which may enhance the risk of a type II error, it is concluded that a potential difference is likely to be very small.

Preterm disparities between foreign and Swedish born mothers depend on the method used to estimate gestational age. A Swedish population-based register study

This study aims to examine whether disparities in gestational age outcomes between foreign and Swedish-born mothers are contingent on the measure used to estimate gestational age and, if so, to identify which maternal factors are associated with the discrepancy. Using population register data, we studied all singleton live births in Sweden from 1992–2012 (n = 1,317,265). Multinomial logistic regression was performed to compare gestational age outcomes classified into very (<32 weeks) and late preterm (32–36 weeks), term and post-term derived from the last menstrual period (LMP) and ultrasound estimates in foreign- and Swedish-born women. Compared to Swedish-born women, foreign-born women had similar odds of very preterm birth (OR: 0.98 [95% CI: 0.98, 1.01]) and lower odds of moderately preterm birth (OR: 0.95 [95% CI: 0.92, 0.98]) based on ultrasound, while higher risks based on LMP (respectively, OR: 1.10 [95% CI: 1.07, 1.14] and 1.09 [95% CI: 1.06, 1.13]). Conclusions on disparities in gestational age-related outcomes by mother’s country of origin depend on the method used to estimate gestational age. Except for very preterm, foreign-born women had a health advantage when gestational age is based on ultrasound, but a health disadvantage when based on LMP. Studies assessing disparities in very preterm birth by migration status are not affected by the estimation method but caution should be taken when interpreting disparities in moderately preterm and preterm birth rates.

Swedish intrauterine growth reference ranges of biometric measurements of fetal head, abdomen and femur

Ultrasonic assessment of fetal growth is an important part of obstetric care to prevent adverse pregnancy outcome. However, lack of reliable reference ranges is a major barrier for accurate interpretation of the examinations. The aim of this study was to create updated Swedish national reference ranges for intrauterine size and growth of the fetal head, abdomen and femur from gestational week 12 to 42. This prospective longitudinal multicentre study included 583 healthy pregnant women with low risk of aberrant fetal growth. Each woman was examined up to five times with ultrasound from gestational week 12 + 3 to 41 + 6. The assessed intrauterine fetal biometric measurements were biparietal diameter (outer–inner), head circumference, mean abdominal diameter, abdominal circumference and femur length. A two-level hierarchical regression model was employed to account for the individual measurements of the fetus and the number of repeated visits for measurements while accounting for the random effect of the identified parameterization of gestational age. The expected median and variance, expressed in both standard deviations and percentiles, for each individual biometric measurement was calculated. The presented national reference ranges can be used for assessment of intrauterine size and growth of the fetal head, abdomen and femur in the second and third trimester of pregnancy.

Adherence to Swedish national pregnancy dating guidelines and management of discrepancies between pregnancy dating methods: a survey study

Background

Swedish national guidelines for pregnancy dating were published in 2010. Follow-up is needed to assess adherence and to identify whether any clinical topics are not covered in the guidelines.

Methods

All units in Sweden that performed ultrasound-based pregnancy dating were asked to complete a web-based questionnaire comprising multiple-response questions and commentary fields. Information was collected regarding baseline information, current and previous clinical practice, and management of discrepancies between last-menstrual-period- and ultrasound-based methods for pregnancy dating.

Results

The response rate was 79%. Half of the units offered first-trimester ultrasound to all pregnant women. However, contrary to the guidelines, the crown–rump length was not used for ultrasound-based pregnancy dating in most units. Instead, ultrasound-based pregnancy dating was performed only if the biparietal diameter was between 21 and 55 mm. Management of discrepancies between methods for pregnancy dating varied widely.

Conclusions

The units reported high adherence to national guidelines, except for early pregnancy dating, for which many units followed unwritten or informal guidelines. The management of discrepancies between last-menstrual-period-based and ultrasound-based estimated day of delivery varied widely. These findings emphasize the need for regular updating of national written guidelines and efforts to improve their implementation in all units.

Methods of gestational age assessment influence the observed association between antiretroviral therapy exposure, preterm delivery, and small-for-gestational age infants: a prospective study in Cape Town, South Africa

PURPOSE

Heterogeneous findings exist on antiretroviral therapy (ART) use in pregnancy and preterm delivery (PTD) or infants born small-for-gestational age (SGA). Whether reported differences may be explained by methods used to ascertain gestational age (GA) has not been explored.

METHODS

We enrolled consecutive pregnant women attending a large primary care antenatal clinic in South Africa. Public-sector midwives assessed GA by last menstrual period (LMP) and symphysis-fundal height (SFH). Separately, if clinical GA was less than 24 weeks, ultrasound (US) was performed by a research sonographer blinded to midwife assessments. In analysis, the impact of measurement error on the association between HIV/ART status and birth outcome by GA method was assessed, and factors associated with clinical GA underestimation or overestimation identified.

RESULTS

In 1787 women included overall, estimated PTD incidence was 36% by LMP, 17% by SFH, and 11% by US. PTD risk was higher for HIV-infected than HIV-uninfected women using US-GA (adjusted odds ratio [aOR] 1.95; 95% CI 1.10-3.46); for LMP/SFH-GA, the associations were smaller and not significant. These findings persisted after adjustment for age, parity, height, and previous PTD. PTD risk did not vary by timing of ART initiation (before or during pregnancy) for any method. Elevated BMI and older age were associated with decreased risk of underestimation by both LMP and SFH; HIV status and obesity were associated with increased risk of overestimation by SFH. There were no differences in SGA incidence across GA methods.

CONCLUSIONS

Findings for an association between HIV/ART and birth outcomes are substantially influenced by GA assessment method. With growing public health interest in this association, future research efforts should seek to standardize optimal measures of gestation.

Discrepancy between pregnancy dating methods affects obstetric and neonatal outcomes: a population-based register cohort study

To assess associations between discrepancy of pregnancy dating methods and adverse pregnancy, delivery, and neonatal outcomes, odds ratios (ORs) with 95% confidence intervals (CIs) were calculated for discrepancy categories among all singleton births from the Medical Birth Register (1995-2010) with estimated date of delivery (EDD) by last menstrual period (LMP) minus EDD by ultrasound (US) -20 to +20 days. Negative/positive discrepancy was a fetus smaller/larger than expected when dated by US (EDD postponed/changed to an earlier date). Large discrepancy was <10^th or >90^th percentile. Reference was median discrepancy ±2 days. Odds for diabetes and preeclampsia were higher in pregnancies with negative discrepancy, and for most delivery outcomes in case of large positive discrepancy (+9 to +20 days): shoulder dystocia [OR 1.16 (95% CI 1.01-1.33)] and sphincter injuries [OR 1.13 (95% CI 1.09-1.17)]. Odds for adverse neonatal outcomes were higher in large negative discrepancy (-4 to -20 days): low Apgar score [OR 1.18 (95% CI 1.09-1.27)], asphyxia [OR 1.18 (95% CI 1.11-1.25)], fetal death [OR 1.47 (95% CI 1.32-1.64)], and neonatal death [OR 2.19 (95% CI 1.91-2.50)]. In conclusion, especially, large negative discrepancy was associated with increased risks of adverse perinatal outcomes.

Maternal and fetal characteristics affect discrepancies between pregnancy-dating methods: a population-based cross-sectional register study

INTRODUCTION

Gestational age is estimated by ultrasound using fetal size as a proxy for age, although variance in early growth affects reliability. The aim of this study was to identify characteristics associated with discrepancies between last menstrual period-based (EDD-LMP) and ultrasound-based (EDD-US) estimated delivery dates.

MATERIAL AND METHODS

We identified all singleton births (n = 1 201 679) recorded in the Swedish Medical Birth Register in 1995-2010, to assess the association between maternal/fetal characteristics and large negative and large positive discrepancies (EDD-LMP earlier than EDD-US and 10th percentile in the discrepancy distribution vs. EDD-LMP later than EDD-US and 90th percentile). Analyses were adjusted for age, parity, height, body mass index, smoking, and employment status.

RESULTS

Women with a body mass index >40 kg/m² had the highest odds for large negative discrepancies (-9 to -20 days) [odds ratio (OR) 2.16, 95% CI 2.01-2.33]. Other factors associated with large negative discrepancies were: diabetes, young maternal age, multiparity, body mass index between 30 and 39.9 kg/m² or <18.5 kg/m² , a history of gestational diabetes, female fetus, shorter stature (<-1 SD), a history of preeclampsia, smoking or snuff use, and unemployment. Large positive discrepancies (+4 to +20 days) were associated with male fetus (OR 1.80, 95% CI 1.77-1.83), age ≥30 years, multiparity, not living with a partner, taller stature (>+1 SD), and unemployment.

CONCLUSIONS

Several maternal and fetal characteristics were associated with discrepancies between dating methods. Systematic associations of discrepancies with maternal height, fetal sex, and partly obesity, may reflect an influence on the precision of the ultrasound estimate due to variance in early growth.