Who is at risk for prolonged and postterm pregnancy?

doi:10.1016/j.ajog.2009.02.034

American Journal of Obstetrics and Gynecology

Volume 200, Issue 6, June 2009, Pages 683.e1-683.e5

Presented at the 75th Annual Meeting of the Pacific Coast Obstetrical and Gynecological Society, Victoria, BC, Canada, Oct. 15-19, 2008.

https://doi.org/10.1016/j.ajog.2009.02.034 Get rights and content

Objective

The objective of the study was to examine risk factors for postterm (gestational age ≥ 42 weeks) or prolonged (gestational age ≥ 41 weeks) pregnancy.

Study Design

We conducted a retrospective cohort study of all term, singleton pregnancies delivered at a mature, managed care organization. The primary outcome measures were the rates of pregnancies greater than 41 or 42 weeks' gestation. Multivariable logistic regression models were used to control for potential confounding and interaction.

Results

Specific risk factors for pregnancy beyond 41 weeks of gestation include obesity (adjusted odds ratio [aOR], 1.26; 95% confidence interval [CI], 1.16-1.37), nulliparity (aOR, 1.46; 95% CI 1.42-1.51), and maternal age 30-39 years (aOR, 1.06; 95% CI, 1.02-1.10) and 40 years or older (aOR, 1.07; 95% CI, 1.02-1.12). Additionally, African American, Latina, and Asian race/ethnicity were all associated with a lower risk of reaching 41 or 42 weeks of gestation.

Conclusion

Our findings suggest that there may be biological differences that underlie the risk for women to progress to 41 or 42 weeks of gestation. In particular, obesity is a modifiable risk factor and could potentially be prevented with prepregnancy or interpregnancy interventions.

Section snippets

Materials and Methods

We designed a retrospective cohort study of all women who delivered singleton pregnancies at 37 weeks' gestational age or greater within the Kaiser Permanente Medical Care Program's (KPMCP) Northern California Region from Jan. 1, 1995, to Dec. 31, 1999. We excluded women with previa or a prior cesarean delivery because of the high proportion of these women who would be delivered prior to 40 weeks of gestation.

Maternal and neonatal demographic data were obtained by scanning the KPMCP

Results

The study cohort consisted of 119,162 women who experienced term births. Forty-five percent of these women delivered between 37 and 39 weeks' gestation, 37% delivered at 40 weeks' gestation, 15% delivered at 41 weeks' gestation, and fewer than 3% delivered at 42 weeks or beyond. In bivariate comparisons there was a statistically significant association between maternal age, race/ethnicity, parity, obesity, chronic hypertension, diabetes mellitus, and fetal sex and having a term pregnancy

Comment

In this cohort of women delivering at 37 weeks or beyond, we found that there were several factors associated with prolonged and postterm pregnancy. Among these, obesity is the 1 truly modifiable risk factor upon which prepregnancy or interpregnancy dietary and exercise behavioral modifications could theoretically improve. Obviously such modifications would have an impact on other health outcomes as well, but because postterm pregnancy is associated with a litany of perinatal complications

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Cited by (93)

Ischemic Heart Disease and Pregnancy: How Do They Interact?
2022, JACC: Advances
Parity and gestational age are associated with vaginal microbiota composition in term and late term pregnancies
2022, eBioMedicine
Citation Excerpt :
Prolonged pregnancy increases the risk of stillbirth, neonatal morbidity and mortality, and the risk of CS associated to the induction of labour is higher than in inductions in earlier pregnancy weeks.66 Nulliparity is one of the known risk factors for prolonged pregnancy,67 and nulliparas form the majority of women undergoing induction of labour due to prolonged pregnancy26 Previously Lactobacillus abundances have been shown to decline gradually toward birth.19 Prevalence of L. crispatus -dominated vaginal microbiota, however, was higher after the due date among nulliparas in our study.
Vaginal microbiota and its potential contribution to preterm birth is under intense research. However, only few studies have investigated the vaginal microbiota in later stages of pregnancy or at the onset of labour.
We used 16S rRNA gene amplicon sequencing to analyse cross-sectional vaginal swab samples from 324 Finnish women between 37–42 weeks of gestation, sampled before elective caesarean section, at the onset of spontaneous labour, and in pregnancies lasting ≥41 weeks of gestation. Microbiota data were combined with comprehensive clinical data to identify factors associated with microbiota variation.
Vaginal microbiota composition associated strongly with advancing gestational age and parity, i.e. presence of previous deliveries. Absence of previous deliveries was a strong predictor of Lactobacillus crispatus dominated vaginal microbiota, and the relative abundance of L. crispatus was higher in late term pregnancies, especially among nulliparous women.
This study identified late term pregnancy and reproductive history as factors underlying high abundance of gynaecological health-associated L. crispatus in pregnant women. Our results suggest that the vaginal microbiota affects or reflects the regulation of the duration of gestation and labour onset, with potentially vast clinical utilities. Further studies are needed to address the causality and the mechanisms on how previous labour, but not pregnancy, affects the vaginal microbiota. Parity and gestational age should be accounted for in future studies on vaginal microbiota and reproductive outcomes.
This research was supported by EU H2020 programme Sweet Crosstalk ITN (814102), Academy of Finland, State Research Funding, and University of Helsinki.
Prolonged and post-term pregnancies: a regional survey of French clinical practices
2021, Gynecologie Obstetrique Fertilite et Senologie
Analyser les pratiques professionnelles au sein d’un réseau de périnatalité sur la prise en charge des grossesses prolongées. L’objectif secondaire était d’évaluer la morbidité néonatale et maternelle en cas de grossesse prolongée.
Étude observationnelle, rétrospective réalisée dans les 23 maternités du réseau de périnatalité entre septembre et décembre 2018. Le critère d’inclusion était un accouchement à un terme ≥ 41⁺⁰ SA. Le critère de jugement principal était la conformité aux recommandations du CNGOF évaluée sur 10 items (conforme si score ≥ 80 %). Les critères de jugement secondaires étaient des critères composites de morbidité néonatale (ventilation, réanimation et/ou score d’Apgar inférieur à 7 à 5 min de vie) et maternelle (lésion obstétricale du sphincter anal et/ou hémorragie du post-partum).
Sur les 596 patientes incluses, 65,3 % des dossiers étaient conformes. Les critères non conformes étaient surtout la recherche d’oligoamnios à l’échographie (46,8 % ; n = 279) et l’information des patientes (14,8 % ; n = 88). La morbidité néonatale concernait 40 nouveau-nés (6,0 %) avec comme facteur de risque la dystocie des épaules (OR = 5,2 ; IC 95 % : 1,4–19,7). La morbidité maternelle concernait 70 patientes (10,6 %) notamment lorsque le travail est allongé (OR = 1,1 par heure de travail ; IC 95 % : 1,02–1,24) et pour les utérus cicatriciels (OR = 4,4 ; IC95 % : 1,8–11,0).
Le rythme de surveillance des grossesses prolongées est en accord avec les recommandations nationales. Les axes d’améliorations sont la recherche d’un oligoamnios par la mesure de la plus grande citerne à l’échographie, et l’information faite aux patientes sur les possibilités de déclenchement.
To assess professional practices of prolonged and post-term pregnancies in accordance to French guidelines. The secondary outcome was to evaluate neonatal and maternal morbidity during prolonged pregnancy.
Descriptive retrospective study was conducted in the 23 maternity hospitals of perinatal network between September and December 2018. The inclusion criterion was a birth term of ≥ 41⁺⁰ weeks of gestation. Primary outcome was conformity to the national guidelines based on 10 items (conformity score ≥ 80%). The secondary outcome was a composite criteria of neonatal morbidity (ventilation, resuscitation and/or Apgar score < 7 at 5 minutes) and maternal morbidity (obstetrical anal sphincter injury and/or postpartum hemorrhage).
A total of 596 patients were included and the conformity was obtained in 65.3% of cases. Inconsistent criteria were amniotic fluid evaluation by the deepest vertical pocket (46.8%, n = 279), and information of patients on prolonged pregnancy management (14.8%, n = 88). Adverse perinatal outcome occurred for 40 newborns (6.0%) with shoulder dystocia (OR = 5.2; CI 95%: 1.4–19.7) as a principal risk factor. Maternal morbidity outcome occurred in 70 cases (10.6%) primarily with increase in labour duration (OR = 1.1 by hour of labour; CI 95%: 1.02–1.24) and prior caesarian section (OR = 4.4; CI 95%: 1.8–11.0).
Management of prolonged and post-term pregnancies matching with the French national guidelines. Points of improvement are amniotic fluid evaluation at term by a single deepest vertical pocket, and the information about induction of labour at term.
The impact of maternal obesity in pregnancy on placental glucocorticoid and macronutrient transport and metabolism
2020, Biochimica et Biophysica Acta - Molecular Basis of Disease
Maternal obesity is the most common metabolic disturbance in pregnancy affecting >1 in 5 women in some countries. Babies born to obese women are heavier with more adiposity at birth, and are vulnerable to obesity and metabolic disease across the lifespan suggesting offspring health is ‘programmed’ by fetal exposure to an obese intra-uterine environment. The placenta plays a major role in dictating the impact of maternal health on prenatal development. Maternal obesity impacts the function of integral placental receptors and transporters for glucocorticoids and nutrients, key drivers of fetal growth, though mechanisms remain poorly understood. This review aims to summarise current knowledge in this area, and considers the impact of obesity on the epigenetic machinery of the placenta at this vital juncture in offspring development. Further research is required to advance understanding of these areas in the hope that the trans-generational cycle of obesity can be alleviated.
The effect of obesity on the onset of spontaneous labor and scheduled delivery rates in term pregnancies
2020, Taiwanese Journal of Obstetrics and Gynecology
Citation Excerpt :
Furthermore, obesity is associated with an increased risk of uterine fibroids, which may affect pregnancy outcomes and require specific clinical management [15,16]. There has also been reported to be an increase in obesity-related post-term pregnancy rates [17,18]. Although the precise cause of the increase in the incidence of post-term pregnancies in obese pregnancies is not fully known, it has been suggested that it could be due to a decrease in the onset of spontaneous labor rates [19,20].
To determine the effect of obesity on the onset of spontaneous labor, scheduled delivery rates and perinatal outcomes in term pregnancies.
242 obese and 244 non-obese pregnant women ≥37 gestational weeks were compared in terms of the onset of spontaneous labor, scheduled delivery rates and perinatal outcomes.
Obese pregnant women had statistically significantly lower onset of spontaneous labor and higher rates of scheduled delivery. No difference was determined in respect of the type of delivery, 1st and 5th minutes APGAR scores and the need for intensive care. Higher values of birth weight, large for gestational age, macrosomia, gestational diabetes mellitus and preeclampsia were determined in obese women.
The onset of spontaneous labor rates in term obese pregnancies were lower and scheduled delivery rates were higher than in the non-obese pregnancies. However, more extensive studies are needed to better understand this relationship.
Hematopoietic changes in the offspring induced by maternal overweight: Effect on placenta and fetal liver populations
2018, Placenta
Bone marrow cells (BMC) from obese adult mice display an increased apoptosis rate over proliferation. Hematopoietic stem cells (HSC) form all blood cells and are important BMC used in cell therapy. Because it is known that prenatal development can be affected by adverse metabolic epigenetic programming from the maternal organism, this work aimed to investigate the effects of maternal overweight on placenta and fetal liver hematopoietic niches.
Overweight was induced in female mice by overfeeding during lactation. After Swiss females were mated with healthy males, fetuses at 19 dpc (day post conception) and placentas were analyzed. Maternal biometric parameters were compared, and hematopoiesis in the dissociated placenta and fetal liver cells was analyzed by flow cytometry. Placenta morphology and protein content were also studied.
The model induced accumulation of adipose tissue, weight gain, and maternal hyperglycemia. Placentas from the overfed group (OG) displayed altered morphology, higher carbohydrate and lipid deposition, and increased protein content of fibronectin and PGC-1α. Cytometric analysis showed that placentas from OG presented a higher percentage of circulating macrophages, endothelial progenitor cells, HSC, and progenitor cells. No difference was detected in the percentage of neutrophil granulocytes and total leukocytes or in the proliferation of total cells, HSC, or total leukocytes. With regard to liver analysis of the OG group, there was a significant increase in circulating macrophages, primitive HSC, and oval cells but no difference in hematopoietic progenitor cells, total leukocytes, or leukocyte or total cell proliferation.
Unregulated maternal metabolism can affect hematopoietic populations within the placenta and fetal liver.

View all citing articles on Scopus

: Reprints not available from the authors.

: This study was supported in part by the Agency for Healthcare Research and Quality Grant P01 HS010856 (Promoting Effective Communication and Decision Making for Diverse Populations). A.B.C. is supported by the Robert Wood Johnson Foundation as a Physician Faculty Scholar. N.E.S. is supported by the National Institute of Child Health and Human Development Grant HD01262 as a Women's Reproductive Health Research Scholar.

: The views expressed herein are those of the authors and do not necessarily represent the official views of the Agency for Healthcare Research and Quality.

: Cite this article as: Caughey AB, Stotland NE, Washington AE, et al. Who is at risk for prolonged and postterm pregnancy? Am J Obstet Gynecol 2009;200:683.e1-683.e5.

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Meeting paperPCOGS paperWho is at risk for prolonged and postterm pregnancy?

Objective

Study Design

Results

Conclusion

Section snippets

Materials and Methods

Results

Comment

Am J Obstet Gynecol

Am J Obstet Gynecol

Am J Obstet Gynecol

Am J Obstet Gynecol

Obstet Gynecol

Am J Obstet Gynecol

Am J Obstet Gynecol

Stillbirths and rate of neonatal deaths in 76,761 postterm pregnancies in Sweden, 1982-1991: a register study

Acta Obstet Gynecol Scand

Complications of term pregnancies beyond 37 weeks of gestation

Obstet Gynecol

Maternal complications of pregnancy increase beyond 40 weeks of gestation in low-risk women

J Perinatol

Management of postterm pregnancy. Number 6, October 1997. American College of Obstetricians and Gynecologists

Int J Gynaecol Obstet

Postterm delivery: a challenge for epidemiologic research

Epidemiology

An estimate of the tendency to repeat postterm delivery

Epidemiology

Meeting paper
PCOGS paper
Who is at risk for prolonged and postterm pregnancy?