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Discrepancy between pregnancy dating methods – correlates and outcomes
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Research group (Dept. of women´s and children´s health), Obstetrics and Reproductive Health Research. Region Vastmanland – Uppsala University, Center for Clinical Research, Hospital of Vastmanland Västerås, Sweden. (Department of Women’s and Children’s Health, Uppsala University, Uppsala, Sweden)ORCID iD: merit.kullinger@kbh.uu.se
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

With the introduction of obstetric ultrasound there has been a shift from last menstrual period-based to ultrasound-based estimation of gestational age. The choice of the method and timing of pregnancy dating is important because it can affect dating precision and perinatal outcomes.

First, when comparing two large population-based cohorts from the Medical Birth Register, from before and after the introduction of ultrasound-based pregnancy dating, male infants on the edge of prematurity did not benefit from progress in medical care as much as female infants in terms of prematurity-related outcomes. This might reflect a bias introduced by the ultrasound-based pregnancy dating method, because of a tendency to overestimate gestational age in pregnancies with a male fetus.

Second, in a large population-based cross-sectional study, the associations of discrepancies between last menstrual period-based and ultrasound-based estimates with variables such as fetal sex and maternal height, indicated that ultrasound-based pregnancy dating introduced systematic errors presumably related to the method’s use of fetal size as a proxy for gestational age. The largest effect estimates were found for maternal obesity in cases of large negative discrepancies.

Third, in a large population-based cohort study, discrepancies between last menstrual period-based and ultrasound-based estimates were associated with several adverse pregnancy, delivery, and neonatal outcomes. Most importantly, a large negative discrepancy was associated with higher odds for neonatal and intrauterine fetal death, as well as for an infant being small for gestational age.

Fourth, in a survey study there was overall good adherence to national guidelines, except for early pregnancy dating. However, the management of discrepancies between methods for pregnancy dating varied widely in clinical practice, which may be due to the lack of national guidelines.

In summary, ultrasound-based dating can be biased by maternal or fetal characteristics. Discrepancies between methods for pregnancy dating may indicate a need for closer monitoring to optimize perinatal care during pregnancy and childbirth.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. , p. 59
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1444
Keywords [en]
pregnancy, gestational age, ultrasound, last menstrual period
National Category
Obstetrics, Gynecology and Reproductive Medicine
Research subject
Obstetrics and Gynaecology
Identifiers
URN: urn:nbn:se:uu:diva-345957ISBN: 978-91-513-0277-5 (print)OAI: oai:DiVA.org:uu-345957DiVA, id: diva2:1190574
Public defence
2018-05-04, Samlingssalen, Psykiatricentrum, ingång 29, Västmanlands sjukhus, Västerås, 13:15 (Swedish)
Opponent
Supervisors
Available from: 2018-04-11 Created: 2018-03-15 Last updated: 2018-04-24
List of papers
1. Maternal and fetal characteristics affect discrepancies between pregnancy-dating methods: a population-based cross-sectional register study
Open this publication in new window or tab >>Maternal and fetal characteristics affect discrepancies between pregnancy-dating methods: a population-based cross-sectional register study
2017 (English)In: Acta Obstetricia et Gynecologica Scandinavica, ISSN 0001-6349, E-ISSN 1600-0412, Vol. 96, no 1, p. 86-95Article in journal (Refereed) Published
Abstract [en]

IntroductionGestational 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 methodsWe identified all singleton births (n=1201679) 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. ResultsWomen with a body mass index >40kg/m(2) had the highest odds for large negative discrepancies (-9 to -20days) [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 39.9kg/m(2) or <18.5kg/m(2), a history of gestational diabetes, female fetus, shorter stature (<-1SD), a history of preeclampsia, smoking or snuff use, and unemployment. Large positive discrepancies (+4 to +20days) were associated with male fetus (OR 1.80, 95% CI 1.77-1.83), age 30years, multiparity, not living with a partner, taller stature (>+1 SD), and unemployment. ConclusionsSeveral 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.

Keywords
Pregnancy dating, pregnancy, gestational age, ultrasonography, prenatal, menstruation, female, humans
National Category
Obstetrics, Gynecology and Reproductive Medicine
Identifiers
urn:nbn:se:uu:diva-315826 (URN)10.1111/aogs.13034 (DOI)000391980100011 ()27696340 (PubMedID)
Available from: 2017-02-21 Created: 2017-02-21 Last updated: 2018-03-15Bibliographically approved
2. Effects of ultrasound pregnancy dating on neonatal morbidity in late preterm and early term male infants: a register-based cohort study
Open this publication in new window or tab >>Effects of ultrasound pregnancy dating on neonatal morbidity in late preterm and early term male infants: a register-based cohort study
2016 (English)In: BMC Pregnancy and Childbirth, ISSN 1471-2393, E-ISSN 1471-2393, Vol. 16, article id 335Article in journal (Refereed) Published
Abstract [en]

Background: Assessing gestational age by ultrasound can introduce a systematic bias due to sex differences in early growth. Methods: This cohort study included data on 1,314,602 births recorded in the Swedish Medical Birth Register. We compared rates of prematurity-related adverse outcomes in male infants born early term (gestational week 37-38) or late preterm (gestational week 35-36), in relation to female infants, between a time period when pregnancy dating was based on the last menstrual period (1973-1978), and a time period when ultrasound was used for pregnancy dating (1995-2010), in order to assess the method's influence on outcome by fetal sex. Results: As expected, adverse outcomes were lower in the later time period, but the reduction in prematurity-related morbidity was less marked for male than for female infants. After changing the pregnancy dating method, male infants born early term had, in relation to female infants, higher odds for pneumothorax (Cohort ratio [CR] 2. 05; 95 % confidence interval [CI] 1.33-3.16), respiratory distress syndrome of the newborn (CR 1.99; 95 % CI 1.33-2. 98), low Apgar score (CR 1.26; 5 % CI 1.08-1.47), and hyperbilirubinemia (CR 1.12; 95 % CI 1.06-1.19), when outcome was compared between the two time periods. A similar trend was seen for late preterm male infants. Conclusion: Misclassification of gestational age by ultrasound, due to size differences, can partially explain currently reported sex differences in early term and late preterm infants' adverse neonatal outcomes, and should be taken into account in clinical decisions and when interpreting study results related to fetal sex.

Keywords
Pregnancy dating, Ultrasound, Gestational age, Antenatal, Infant, Morbidity
National Category
Obstetrics, Gynecology and Reproductive Medicine
Identifiers
urn:nbn:se:uu:diva-308914 (URN)10.1186/s12884-016-1129-z (DOI)000386858200001 ()27799069 (PubMedID)
Funder
The Karolinska Institutet's Research Foundation
Available from: 2016-12-01 Created: 2016-12-01 Last updated: 2018-03-15Bibliographically approved
3. Adherence to Swedish national pregnancy dating guidelines and management of discrepancies between pregnancy dating methods: a survey study
Open this publication in new window or tab >>Adherence to Swedish national pregnancy dating guidelines and management of discrepancies between pregnancy dating methods: a survey study
2019 (English)In: Reproductive Health, ISSN 1742-4755, E-ISSN 1742-4755, Vol. 16, article id 95Article in journal (Refereed) Published
Abstract [en]

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 88% (38/43 units). 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. Ultrasound-based pregnancy dating was performed only if the biparietal diameter was between 21 and 55 mm. The methods for 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.

National Category
Obstetrics, Gynecology and Reproductive Medicine
Identifiers
urn:nbn:se:uu:diva-345956 (URN)10.1186/s12978-019-0760-3 (DOI)000474617600001 ()31272510 (PubMedID)
Projects
Discrepancy between pregnancy dating methods – correlates and outcomes
Available from: 2018-03-13 Created: 2018-03-13 Last updated: 2019-08-21Bibliographically approved
4. Discrepancy between pregnancy dating methods affects obstetric and neonatal outcomes: a population-based register cohort study
Open this publication in new window or tab >>Discrepancy between pregnancy dating methods affects obstetric and neonatal outcomes: a population-based register cohort study
2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 6936Article in journal (Refereed) Published
Abstract [en]

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 <10th or >90th 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. 

National Category
Obstetrics, Gynecology and Reproductive Medicine
Identifiers
urn:nbn:se:uu:diva-345955 (URN)10.1038/s41598-018-24894-y (DOI)000431204500016 ()29720591 (PubMedID)
Projects
Discrepancy between pregnancy dating methods – correlates and outcomes
Available from: 2018-03-13 Created: 2018-03-13 Last updated: 2018-07-25Bibliographically approved

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