Maternal pre-gravid body mass index and obstetric outcomes in twin gestations

Global and regional incidence of intrahepatic cholestasis of pregnancy: a systematic review and meta-analysis

BACKGROUND

Intrahepatic cholestasis of pregnancy (ICP) can be a source of significant distress for both pregnant women and the fetus, impairing the quality of life and well-being of pregnant women, leading to psychological disorders among pregnant women with severe or recurrent ICP, and causing life-threatening complications among fetuses. Regrettably, our current understanding of ICP globally is limited, lacking a comprehensive estimation of its incidence. Therefore, in this systematic review and meta-analysis, we aimed to investigate the global and regional incidence of ICP and identify factors that account for its variety across studies.

METHODS

A comprehensive search strategy was implemented across PubMed, Scopus, and Web of Science databases. To stabilize the variance, the Freeman-Tukey double arcsine transformation was employed. Subgroup analyses were conducted based on continent, publication type, study design and timing, regional classifications, developmental status, and World Bank income grouping. A multivariate meta-regression analysis was performed to estimate the effects of the continuous moderators on the effect size.

RESULTS

A total of 42,972,872 pregnant women were analyzed from 302 studies. The overall pooled incidence [95% confidence interval] of ICP was 2.9% [2.5, 3.3]. Studies with larger sample sizes tended to provide significantly lower estimates of ICP incidence: 1.6% [1.3, 2] vs 4.7% [3.9, 5.5]. Asia had the highest incidence of ICP among the continents, whereas Oceania had the lowest. Countries that were classified as developed and with higher income had a lower incidence of ICP than those classified as developing and low and middle income.

CONCLUSIONS

The findings of this study will provide valuable insights into the current knowledge regarding the association of the quality of public health and socioeconomic variations with the incidence of ICP on a global scale.

Association between obesity in women with multiple gestations and adverse obstetric outcomes: a study of an American population database with over 136,000 unique deliveries

PURPOSE

The purpose of this study is to compare obese and non-obese women with multiple pregnancies to determine the effects on pregnancy, delivery, and neonatal outcomes.

METHODS

We conducted a retrospective population-based study utilizing data collected between 2004 and 2014 inclusively, from the Healthcare Cost and Utilization Project-Nationwide Inpatient Sample. A total of 137,303 multiple pregnancies were analyzed; 130,542 (95%) were non-obese, while 6761 (5%) were obese. An initial analysis was performed to identify the prevalence of obesity in women with multiple pregnancies. Subsequently, chi-square tests and binary logistic regression analyses were conducted to assess the association between obesity and multiple gestation in the context of obstetric complications.

RESULTS

There was a statistically significant increase in the prevalence of obesity for women with multiple gestations (p < 0.0001). The obese group was at higher risk of pregnancy-induced hypertension (adjusted odd's ratio [aOR] = 1.89, 95% confidence interval [CI] = 1.77-2.02), gestational hypertension (aOR = 1.84, CI = 1.65-2.05), preeclampsia (aOR = 1.68, CI = 1.55-1.81), preeclampsia or eclampsia superimposed on pre-existing hypertension (aOR = 1.86, CI = 1.58-2.20), gestational diabetes mellitus (aOR = 2.65, CI = 2.44-2.87), and placenta previa (aOR = 0.57, CI = 0.39-0.85). They were more likely to have preterm premature rupture of membranes (aOR = 1.19, CI = 1.06-1.34), chorioamnionitis (aOR = 1.24, CI = 1.03-1.51), caesarean deliveries (aOR = 1.28, CI = 1.18-1.38), wound complications (aOR = 1.65, CI = 1.31-2.08), and transfusions (aOR = 0.77, CI = 0.67-0.89). They were less likely to have small for gestational age neonates (aOR = 0.88, CI = 0.79-0.97), though more likely to have neonates with congenital anomalies (aOR = 1.56, CI = 1.16-2.10).

CONCLUSION

Obesity and multiple gestations are independent risk factors for adverse obstetric outcomes. Combined, when analyzed in a large population, obesity in multiple gestation increases the risk of maternal, delivery, and neonatal complications.

The association between maternal obesity and fetomaternal outcomes in twin pregnancies

The prevalence of overweight and obese people worldwide has dramatically increased in the last decades and is yet to peak. At the same time and partly due to obesity and associated assisted reproduction, twinning rates showed a clear rise in the last years. Adverse fetomaternal outcomes are known to occur in singleton and twin pregnancies in overweight and obese women. However, the impact of the obesity levels as defined by the World Health Organization on the outcomes of twin pregnancies has not been thoroughly studied. Therefore, the purpose of this study is to examine how maternal overweight, and the level of obesity affect fetomaternal outcomes in twin pregnancies, hypothesizing a higher likelihood for adverse outcomes with overweight and each obesity level. This is a retrospective cohort study with 2,349 twin pregnancies that delivered at the Buergerhospital Frankfurt, Germany between 2005 and 2020. The mothers were divided into exposure groups depending on their pre-gestational body mass index; these were normal weight (reference group), overweight and obesity levels I, II, and III. A multivariate logistic regression analysis was performed to assess the influence of overweight and obesity on gestational diabetes mellitus, preeclampsia, postpartum hemorrhage, intrauterine fetal death, and a five-minutes Apgar score below seven. The adjusted odds ratio for gestational diabetes compared to normal weight mothers were 1.47, 2.79, 4.05, and 6.40 for overweight and obesity levels I, II and III respectively (p = 0.015 for overweight and p < 0.001 for each obesity level). Maternal BMI had a significant association with the risk of preeclampsia (OR 1.04, p = 0.028). Overweight and obesity did not affect the odds of postpartum hemorrhage, fetal demise, or a low Apgar score. While maternal overweight and obesity did not influence the fetal outcomes in twin pregnancies, they significantly increased the risk of gestational diabetes and preeclampsia, and that risk is incremental with increasing level of obesity.

Association Between Maternal Body Mass Index and Fetal Acidosis in Term Twin Pregnancies: A Retrospective Cohort Study

OBJECTIVES

Given the increased risk of fetal acidosis in singleton neonates born to pregnant people with an elevated BMI, our objective was to evaluate the association between pre-pregnancy/first-trimester BMI and fetal acidosis among term twin pregnancies.

METHODS

Retrospective study of pregnant people with twin gestation and their term infants admitted to our centre between 2014 and 2019. Using a generalized estimating equation, the association between maternal BMI and fetal acidosis was determined using odds ratios (ORs) with 95% CIs. A two-sided P < 0.05 was considered significant.

RESULTS

A total of 275 pregnant people and 550 infants were analyzed. The number (%) of pregnancies in each BMI class were 10 (4%) underweight, 155 (56%) normal weight, 66 (24%) overweight, 22 (8%) class I, 9 (3%) class II, and 13 (5%) class III. The prevalence of maternal diabetes and hypertension was highest in class III (31%) and class II (44%), respectively. Fetal acidosis was diagnosed in 35 (6%) infants. After adjusting for confounders (maternal age, diabetes, and hypertension), infants born to those with elevated BMI did not have increased odds of fetal acidosis compared to those born to underweight and normal weight group (OR 1.29; 95% CI 0.38-4.41 for class I, P = 0.67 and OR 2.80; 95% CI 0.62-12.62 for the combined classes II and III, P = 0.18).

CONCLUSIONS

Maternal BMI was not associated with fetal acidosis in term twin pregnancies. Further research is required to corroborate study findings due to small sample size.

Risk factors for adverse outcomes in twin pregnancies: a narrative review

PURPOSE

Globally, the incidence of twin pregnancies is rising owing to the use of assisted reproductive technologies (ART), emigration and deferment of pregnancy until advanced maternal age (AMA). While twin pregnancies have higher absolute risks of adverse outcomes, including miscarriage, stillbirth, neonatal death and preterm delivery, the impact of specific exposures and risk factors related to these outcomes may differ between twin pregnancies and singleton pregnancies. Regarding modifiable factors, data are sometimes based on evidence extrapolated from singleton or whole obstetric populations. Therefore, targeted evidence is required to provide care tailored to twin pregnancies to prevent adverse outcomes. We aimed to comprehensively review the association between different risk factors and adverse outcomes in twin pregnancies, including data on chorionicity, and to compare these to singletons.

MATERIALS AND METHODS

This review examines the risks associated with chorionicity, AMA, body mass index (BMI), socioeconomic and ethnic inequalities, maternal smoking, use of ART, maternal perception of fetal movement, and maternal comorbidities, including hypertensive disorders of pregnancy (HDP) and gestational diabetes mellitus (GDM). Adverse outcomes reported were preterm birth, admission to the neonatal intensive care unit (NICU), stillbirth and neonatal mortality. As such, fetal mortality and morbidity will be under-represented, as pregnancy loss before 22-24 weeks is omitted.

RESULTS

Monochorionicity increases the risk of stillbirth, NICU admission, and preterm delivery in twin pregnancy. AMA predisposes twin pregnancies to higher risks of mortality, admission to the NICU, and preterm birth than singleton pregnancies do. Conversely, the impact of BMI, socioeconomic inequalities, smoking, ART, and HDP on adverse outcomes appears to be lower in twin pregnancies than in singleton pregnancies. This attenuation might be explained by the higher baseline risk of adverse outcomes such as preterm birth in twin pregnancies. Some exposures, such as ART use and GDM, appear to be "protective" against perinatal mortality in twin pregnancies, despite being established risk factors for adverse outcomes in singleton pregnancies, potentially related to access to specialist care. There is a paucity of evidence available to counsel mothers of twin pregnancies regarding reduced fetal movement.

CONCLUSIONS

Overall, the risk factors for adverse pregnancy outcomes differ between twin and singleton pregnancies. This highlights the need for further studies to examine the association between risk factors and adverse outcomes in twin pregnancies. The resulting data would facilitate tailored guidance for twin pregnancies, contribute to improved antenatal care, and inform wider public health strategies.

Pre-pregnancy body mass index and adverse maternal and perinatal outcomes in twins: A population retrospective cohort study

OBJECTIVE

To examine the association between pre-pregnancy BMI and severe maternal morbidity (SMM), perinatal death and severe neonatal morbidity in twin pregnancies.

METHODS

All twin births at ≥ 20 weeks gestation in British Columbia, Canada, from 2000 to 2017 were included. We estimated rates of SMM, a perinatal composite of death and severe morbidity, and its components per 10,000 pregnancies. Confounder-adjusted rate ratios (aRR) between pre-pregnancy BMI and outcomes were estimated using robust Poisson regression.

RESULTS

Overall, 7770 (368 underweight, 1704 overweight, and 1016 obese) women with twin pregnancy were included. The rates of SMM were: 271.1, 320.4, 270.0, and 225.9 in underweight, normal BMI, overweight and obese women, respectively. There was little association between obesity and any of the primary outcomes (e.g., aRR = 1.09, 95% CI = 0.85, 1.38 for composite perinatal outcome). Underweight women had higher rates of the composite perinatal adverse outcome (aRR = 1.79, 95% CI = 1.32-2.43), driven by increased rates of severe respiratory distress syndrome, and neonatal death.

CONCLUSIONS

There was no evidence of elevated risk of adverse outcomes among twin pregnancies of women who were overweight or obese. Risk was higher in underweight women, who may require specific care when carrying twins.

Risk Factors for Maternal Body Mass Index and Gestational Weight Gain in Twin Pregnancies

Objective This retrospective cohort study analyzes risk factors for abnormal pre-pregnancy body mass index and abnormal gestational weight gain in twin pregnancies.

Methods Data from 10 603/13 682 twin pregnancies were analyzed using uni- and multivariable logistic regression models to determine risk factors for abnormal body mass index and weight gain in pregnancy.

Results Multiparity was associated with pre-existing obesity in twin pregnancies (aOR: 3.78, 95% CI: 2.71 – 5.27). Working in academic or leadership positions (aOR: 0.57, 95% CI: 0.45 – 0.72) and advanced maternal age (aOR: 0.96, 95% CI: 0.95 – 0.98) were negatively associated with maternal obesity. Advanced maternal age was associated with a lower risk for maternal underweight (aOR: 0.95, 95% CI: 0.92 – 0.99). Unexpectedly, advanced maternal age (aOR: 0.98, 95% CI: 0.96 – 0.99) and multiparity (aOR: 0.6, 95% CI: 0.41 – 0.88) were also associated with lower risks for high gestational weight gain. Pre-existing maternal underweight (aOR: 1.55, 95% CI: 1.07 – 2.24), overweight (aOR: 1.61, 95% CI: 1.39 – 1.86), obesity (aOR: 3.09, 95% CI: 2.62 – 3.65) and multiparity (aOR: 1.64, 95% CI: 1.23 – 2.18) were all associated with low weight gain. Women working as employees (aOR: 0.85, 95% CI: 0.73 – 0.98) or in academic or leadership positions were less likely to have a low gestational weight gain (aOR: 0.77, 95% CI: 0.64 – 0.93).

Conclusion Risk factors for abnormal body mass index and gestational weight gain specified for twin pregnancies are relevant to identify pregnancies with increased risks for poor maternal or neonatal outcome and to improve their counselling. Only then, targeted interventional studies in twin pregnancies which are desperately needed can be performed.

Maternal Obesity in Twin Pregnancy: The Role of Nutrition to Reduce Maternal and Fetal Complications

There are more and more obese mothers with twin gestations. For a long time before, the responses of lymphocytes and platelets in obese women can cause a low-grade inflammation. In addition, a proper control of gestational weight gain would improve the outcomes in mothers with high pre-gestational body mass index (BMI). In women with high pre-gestational BMI and twin pregnancy, our aims were to explore the biochemical and hematological parameters and to study the rate of obstetric adverse outcomes. This was an observational and retrospective study conducted in the Hospital Universitario La Paz (Madrid, Spain). We included 20 twin pregnancies as the lean group (BMI = 18.5–24.9 kg/m²), homogeneous in the maternal age and ethnicity, and having parity with other 20 twin pregnancies as the obese group (BMI ≥ 30 kg/m²). The maternal data and maternal, fetal, obstetric, and neonatal complications were collected from the medical records. In the first and third trimester of pregnancy, the biochemical and hematological parameters of the blood were assayed. In this cohort, gestational weight gain was significantly lower in the obese than lean group. In the first trimester, the hemoglobin levels in obese women (12.1 ± 0.8 g/dL) were lower than lean women (12.6 ± 0.7 g/dL; p-Value = 0.048). In addition, the tendency of glucose levels, TSH levels and platelets was to increase in obese compared to lean women. In the third trimester, the TSH levels were higher in obese (3.30 ± 1.60 mUI/L) than lean women (1.70 ± 1.00 mUI/L; p-Value = 0.009). Furthermore, there was a tendency for levels of platelets and lymphocytes to increase in obese compared to lean women. No significant differences were detected in the rate of maternal, fetal, obstetrical, and neonatal complications between the groups. The hemoglobin, platelets, lymphocytes and TSH levels need further investigation to understand potential subclinical inflammation in obese women. Furthermore, obese women with twin pregnancies should follow-up with a specialist nutritionist, to help them control their gestational weight gain with appropriate dietary measures.

Special Considerations Regarding Antenatal Care and Pregnancy Complications in Dichorionic Twin Pregnancies

Twin pregnancies account for about 3.3% of all deliveries in the United States with the majority of them being dichorionic diamniotic (DCDA). Maternal physiological adaption in twin pregnancies is exaggerated and the rate of almost every maternal and fetal complication is higher when compared to singleton pregnancies. Therefore, twin pregnancies necessitate closer antenatal surveillance by care providers who are familiar with the specific challenges unique to these pregnancies, and there is evidence that following women with twins in a specialized twin clinic can result in improved obstetrical outcomes. The importance of the first antenatal visit in twin pregnancies cannot be over emphasized and should preferably take place early in gestation as it is the optimal period to correctly identify the number of fetuses and the type of placentation (chorionicity and amnionicity). This will allow the patients, families, and caregivers to make the appropriate modifications and to tailor an optimal antenatal follow-up plan. This plan should focus on general recommendations such as weight gain and level of activity, education regarding complications specific to twin pregnancies along with the relevant symptoms and indications to seek care, as well as on close maternal and fetal monitoring. In this review, we summarize available evidence and current guidelines regarding antenatal care in DCDA twin pregnancies.

Perinatal Outcomes and Risk Factors for Preterm Birth in Twin Pregnancies in a Chinese Population: A Multi-center Retrospective Study

Background: Twin pregnancies are associated with an increased risk of adverse maternal and neonatal outcomes, mainly owing to prematurity. Few studies have evaluated the risk factors for preterm birth (PTB) in Chinese population. The objective of this study is to present the short-term maternal-neonatal outcomes, investigating the potential risk factors associated with preterm birth in Chinese twin pregnancies.

Methods: A multi-center retrospective study of women pregnant with twins ≥28 weeks of gestation was conducted. Maternal and neonatal outcomes were analyzed. Logistic regression was used to identify potential risk factors for PTB before 37, 34, and 32 weeks, respectively.

Results: A total of 3,288 twin pregnancies and 6,576 neonates were included in 99,585 pregnancies. The rate of twin pregnancy was 3.3%, while the PTB rate before 37, 34, and 32 weeks among this population were 62.1, 18.8, and 10.4%, respectively. Logistic regression revealed that monochorionicity [Odds ratio (OR) 3.028, 95% confident interval (CI) 2.489–3.683, P < 0.001], gestational weight gain (GWG) <10 kg (OR 2.285, 95% CI 1.563–3.339, P < 0.001) and GWG between 10 and 15 kg (OR 1.478, 95% CI 1.188–1.839, P < 0.001), preeclampsia (PE) (OR 3.067, 95% CI 2.142–4.390, P < 0.001), and intrahepatic cholestasis of pregnancy (ICP) (OR 3.122, 95% CI 2.121–4.596, P < 0.001) were the risk factors for PTB before 37 weeks. Monochorionicity (OR 2.865, 95% CI 2.344–3.501, P < 0.001), age < 25 years (OR 1.888, 95% CI 1.307–2.728, P = 0.001), and GWG <10 kg (OR 3.100, 95% CI 2.198–4.372, P < 0.001) were risk factors for PTB before 34 weeks. Monochorionicity (OR 2.566, 95% CI 1.991–3.307, P < 0.001), age younger than 25 years (OR 1.964, 95% CI 1.265–3.048, P = 0.003), and GWG <10 kg (OR 4.319, 95% CI 2.931–6.364, P < 0.001) were the risk factors for PTB before 32 weeks.

Conclusions: Monochorionicity and GWG <10 kg were two major risk factors for PTB before 32, 34, and 37 weeks, whereas maternal age, PE, and ICP were also risk factors for PTB in specific gestational age.

Guideline No. 391-Pregnancy and Maternal Obesity Part 1: Pre-conception and Prenatal Care

OBJECTIVE

This guideline will review key aspects in the pregnancy care of women with obesity. Part I will focus on pre-conception and pregnancy care. Part II will focus on team planning for delivery and Postpartum Care.

INTENDED USERS

All health care providers (obstetricians, family doctors, midwives, nurses, anaesthesiologists) who provide pregnancy-related care to women with obesity.

TARGET POPULATION

Women with obesity who are pregnant or planning pregnancies.

EVIDENCE

Literature was retrieved through searches of Statistics Canada, Medline, and The Cochrane Library on the impact of obesity in pregnancy on antepartum and intrapartum care, maternal morbidity and mortality, obstetrical anaesthesia, and perinatal morbidity and mortality. Results were restricted to systematic reviews, randomized controlled trials/controlled clinical trials, and observational studies. There were no date or language restrictions. Searches were updated on a regular basis and incorporated in the guideline to September 2018. Grey (unpublished) literature was identified through searching the websites of health technology assessment and related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALIDATION METHODS

The content and recommendations were drafted and agreed upon by the authors. Then the Maternal-Fetal Medicine Committee peer reviewed the content and submitted comments for consideration, and the Board of the Society of Obstetricians and Gynaecologists of Canada (SOGC) approved the final draft for publication. Areas of disagreement were discussed during meetings, at which time consensus was reached. The level of evidence and quality of the recommendation made were described using the Evaluation of Evidence criteria of the Canadian Task Force on Preventive Health Care.

BENEFITS, HARMS, AND COSTS

Implementation of the recommendations in these guidelines may increase obstetrical provider recognition of the issues affected pregnant individuals with obesity, including clinical prevention strategies, communication between the health care team, the patient and family as well as equipment and human resource planning. It is hoped that regional, provincial and federal agencies will assist in the education and support of coordinated care for pregnant individuals with obesity.

GUIDELINE UPDATE

SOGC guidelines will be automatically reviewed 5 years after publication. However, authors can propose another review date if they feel that 5 years is too short/long based on their expert knowledge of the subject matter.

SPONSORS

This guideline was developed with resources funded by the SOGC.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Challenges for better care based on the course of maternal body mass index, weight gain and multiple outcome in twin pregnancies: a population-based retrospective cohort study in Hessen/Germany within 15 years

Introduction

Studies on maternal weight, gestational weight gain and associated outcomes in twin pregnancies are scarce. Therefore, we analyzed these items in a large cohort.

Methods

Data from 10,603/13,725 total twin pregnancies from the perinatal database in Hessen, Germany between 2000 and 2015 were used after exclusion of incomplete or non-plausible data sets. The course of maternal and perinatal outcomes was evaluated by linear and logistic regression models.

Results

The rate of twin pregnancies increased from 1.5 to 1.9% (p < 0.00001). Mean maternal age and pre-pregnancy weight rose from 31.4 to 32.9 years and from 68.2 to 71.2 kg, respectively (p < 0.001). The rates of women with a body mass index ≥ 30 kg/m² increased from 11.9 to 16.9% with a mean of 24.4–25.4 kg/m² (p < 0.001). The overall increase of maternal weight/week was 568 g, the 25th quartile was 419, the 75th quartile 692 g/week. The total and secondary caesareans increased from 68.6 to 73.3% and from 20.6 to 39.8%, respectively (p < 0.001). Rates of birthweight < 1500 g and of preterm birth < 28 and from 28 to 33 + 6 weeks all increased (p < 0.01). No significant changes were observed in the rates of stillbirth, perinatal mortality and NICU admissions.

Conclusion

The global trend of the obesity epidemic is equally observed in German twin pregnancies. The increase of mean maternal weight and the calculated quartiles specific for twin pregnancies help to identify inadequate weight gain in twin gestations. Policy makers should be aware of future health risks specified for singleton and twin gestations.

The combined impact of maternal age and body mass index on cumulative live birth following in vitro fertilization

BACKGROUND

It is critical to evaluate the combined impact of age and body mass index on the cumulative likelihood of live birth following in vitro fertilization, as achieving a lower body mass index before infertility treatment often is recommended for women with overweight and obesity. It is important to consider whether achieving a particular body mass index, thus resulting in an older age at in vitro fertilization cycle start, is beneficial or harmful to the likelihood of live birth.

OBJECTIVES

To evaluate the combined impact of age and body mass index on the cumulative live birth rate following in vitro fertilization to inform when delaying in vitro fertilization treatment to achieve a lower body mass index may be beneficial or detrimental to the likelihood of live birth.

STUDY DESIGN

This is a retrospective study using linked fresh and cryopreserved/frozen cycles from January 2014 to December 2015 from the Society for Reproductive Technology Clinic Outcome Reporting System, representing >90% of in vitro fertilization cycles performed in the United States. The primary outcome was live birth as measured by cumulative live birth rate. Secondary outcomes included implantation rate, clinical pregnancy rate, and miscarriage rate. Poisson and logistic regression were used to calculate risk and odds ratios with 95% confidence intervals to determine differences in implantation, clinical pregnancy, and miscarriage, as appropriate, among first fresh in vitro fertilization cycles compared across age (years) and body mass index (kg/m²) categories. Cox regression was used to calculate hazard ratios with 95% confidence intervals to determine differences in the cumulative live birth rate using fresh plus linked frozen embryo transfer cycles.

RESULTS

There were 51,959 first fresh cycles using autologous eggs and 16,067 subsequent frozen embryo transfer cycles. There were 21,395 live births, for an overall cumulative live birth rate of 41.2% per cycle start. The implantation rate, clinical pregnancy rate, and cumulative live birth rate decreased with increasing body mass index and age, and the miscarriage rate increased with increasing body mass index and age (linear trend P<.001 for all). Body mass index had a greater influence on live birth at younger ages as compared with older ages.

CONCLUSIONS

Age-related decline in fertility has a greater impact than body mass index on the cumulative live birth rate at older ages, suggesting that taking time to achieve lower body mass index before in vitro fertilization may be detrimental for older women with overweight or obesity. Delaying conception to lose weight before in vitro fertilization should be informed by the combination of age and body mass index.

The gestational weight gain and perinatal outcomes among underweight women with twin pregnancies: Propensity score matched analysis from a three-year retrospective cohort

OBJECTIVE

No recommendations are available for gestational weight gain (GWG) in underweight women with twin pregnancies. We aimed to evaluate whether underweight women with twin pregnancies should gain more weight than normal-weight women in order to optimize perinatal outcomes.

STUDY DESIGN

This retrospective cohort study compared the GWG and perinatal outcomes among normal-weight and underweight women who gave birth to viable twins between 2015 and 2018 at the Maternal and Child Health Hospital in Foshan, China. Gestational weight gain (GWG) was categorized as adequate or inadequate GWG, based on the US Institute of Medicine 2009 guidelines for normal-weight women (≥ 0.46 kg/week). The outcomes of interest included spontaneous preterm birth (sPTB) <37 weeks, <35 and <32 weeks, small for gestational age (SGA), gestational hypertensive disorder (GHD), gestational diabetes mellitus (GDM), birth weight discordance (BDW) ≥20%, neonatal intensive unit (NICU) admission and neonatal respiratory distress syndrome (NRDS). Propensity score matching (PSM, in a 1:1 ratio) was utilized to minimize the effects of confounders on the differences in the two cohorts. Multivariable logistic models were also used to verify the results from PSM analysis.

RESULTS

There were 475 normal-weight and 111 underweight women included in the analysis. Our results suggested that the incidence of adequate GWG was comparable between underweight and normal-weight women (37.5% vs. 45.1%, P = 0.141). The prevalence of GDM was significantly lower among underweight women (9.9%) than among normal-weight women (20.4%) (P = 0.010). There was no evidence of differences in other perinatal outcomes between the two groups. 102 underweight women and 102 normal-weight women were included in PSM analyses. There was a lower incidence of GDM in underweight women than in normal-weight women, but the difference was not significant (9.8% vs. 18.6%, P = 0.071). No evidence of any differences in the other outcomes, including sPTB, GHD, BWD≥20%, SGA, NICU admission and NRDS, was found between the underweight and normal-weight women. Multivariable logistic regression models yielded similar results.

CONCLUSIONS

For Chinese twin pregnant women with twin pregnancies, our data does provide evidence to suggest underweight women need to gain more weight than normal-weight women to optimize perinatal outcomes. Future studies with larger number of underweight women with twin gestations are warranted to establish an optimal range of GWG.

Influence of maternal obesity and metabolic and vascular mediators in twin-twin transfusion syndrome

Obesity is a risk factor for complications in singleton and twin pregnancies; however, there are limited data regarding maternal body mass index (BMI) in the setting of twin-twin transfusion syndrome (TTTS). We hypothesized that increased BMI in TTTS is associated with adverse perinatal outcomes and vascular pathology. A retrospective study of twin reversed arterial perfusion (n = 4), selective intrauterine growth restriction (n = 10) and TTTS (n = 33) was conducted. Treatment included fetoscopic laser photocoagulation (FLP) (n = 35) or Solomon technique (n = 12). Ex vivo placental intravascular injections, immunohistochemistry, and perinatal outcomes were compared by maternal BMI. In pregnancy complicated by TTTS, 16/33 women were obese (BMI > 30 kg/m²) and 11/33 were overweight (BMI 25-29.9 kg/m²). Women who were overweight or obese had an increased rate of premature rupture of membranes (PPROM), cesarean delivery, and/or concomitant co-morbidities when compared to the normal weight group. Duration of neonatal intensive care unit (NICU) admission was longer in neonates of overweight/obese women versus normal weight. Placental examination of FLP sites in the obese group showed larger infarcts, increased adipose triglyceride lipase, and a proangiogenic phenotype. Increased BMI is common in our TTTS cohort and it is associated with higher rate of co-morbidity, PPROM, prolonged NICU stay, and an imbalance of placental metabolic and vascular mediators.

The relationship between maternal body mass index and pregnancy outcomes in twin compared with singleton pregnancies

OBJECIVE

Women with twins have an a priori increased risk for many of the complications associated with maternal obesity. Thus, the impact of maternal obesity in twins may differ from that reported in singletons. In addition, given the increased metabolic demands in twin pregnancies, the impact of maternal underweight may be greater in twin compared with singleton gestations. Our objective was to test the hypothesis that the relationship between maternal pre-pregnancy body mass index (BMI) and adverse pregnancy outcomes differ between twin and singleton gestations.

METHODS

This was a retrospective population-based study of all women who had a singleton or twin hospital birth in Ontario, Canada, between April 2012 and March 2016. Data were obtained from the Better Outcomes Registry & Network (BORN) Ontario. The relationship between maternal BMI category and pregnancy complications was assessed separately in twin and singleton gestations. The primary outcome was a composite variable that included any of the following complications: preeclampsia, gestational diabetes, or preterm birth before 32^0/7 weeks. Relative risk (aRR) and 95% confidence intervals (CI) for adverse outcomes for each BMI category as defined by WHO (using normal weight category as reference) were generated using modified Poisson regression, adjusting for maternal age, nulliparity, smoking, previous preterm birth, and fetal sex.

RESULTS

A total of 487,870 women with singleton (n = 480,010) and twin (n = 7860) pregnancies met the inclusion criteria. The risk of the composite primary outcome, preeclampsia, gestational diabetes, and cesarean delivery increased with high maternal BMI in both singleton and twin gestations, but these associations were weaker in twin compared with singleton gestations (association of BMI ≥ 40.0 kg/m² with primary outcome: aRR = 3.10, 95%-CI 2.96-3.24 in singletons compared with aRR = 1.74, 95%-CI 1.37-2.20 in twins). In singleton pregnancies the risk of preterm birth at < 32^0/7 weeks increased with maternal BMI, mainly due to an increased risk of provider-initiated preterm birth. In twin gestations, however, underweight (but not overweight or obesity) was associated with the greatest risk of preterm birth at < 32 weeks (aRR 1.67, 95%-CI 1.17-2.37), mainly due to an increased risk of spontaneous preterm birth (aRR 2.10, 95%-CI 1.44-3.08).

CONCLUSION

In healthy women with twin pregnancies, underweight is associated with the greatest risk for preterm birth, while the association of maternal obesity with adverse pregnancy outcomes is weaker than that observed in singletons.

Maternal BMI in Twin Pregnancies and Impact on Neonatal Outcomes in the Level I Unit: A Retrospective Cohort Study

OBJECTIVE

With maternal obesity rates and twin pregnancies on the rise, the aim of this study was to assess the impact of pre-pregnancy or first trimester BMI on short-term neonatal morbidities in twins admitted to a level I unit.

METHODS

This retrospective single-centre cohort study was conducted on twins born between January 1, 2010 and December 31, 2013 and admitted to the level I unit at Mount Sinai Hospital in Toronto, Ontario. Twin pairs were categorized according to maternal BMI: underweight (<18.5 kg/m²), normal weight (18.5-24.9 kg/m²), overweight (25.0-29.9 kg/m²), and obese (≥30 kg/m²). The primary outcome was combined neonatal morbidities of hypoglycemia and hyperbilirubinemia. The secondary outcome was length of hospital stay. All outcomes were compared between twins in various BMI groups, and data were analyzed using the chi-square test or ANOVA (Canadian Task Force Classification II-2).

RESULTS

Data on 700 neonates born to 350 women were analyzed. Baseline maternal and neonatal characteristics were similar between the groups, except for a statistically significantly higher incidence of maternal hypertension (P < 0.02) and a trend towards increased gestational diabetes rates (P = 0.05) in women with overweight or obesity compared with women with underweight or normal weight. No association was noted between maternal BMI and occurrence of neonatal hypoglycemia, hyperbilirubinemia, and length of stay in either twin pair (P > 0.05) CONCLUSION: Maternal BMI had no detectable effect on neonatal morbidities and length of stay in twins admitted to the level I unit in the study centre.

The Risk of Spontaneous Preterm Birth according to Maternal Pre-pregnancy Body Mass Index in Twin Gestations

BACKGROUND

Maternal obesity is a well-known risk factor for both total preterm birth (PTB) and spontaneous PTB in singleton gestation, whereas this association is not well determined in multiple pregnancy. The objective of this study was to determine the risk of spontaneous PTB according to the pre-pregnancy body mass index (BMI) in twin gestations.

METHODS

The association between the risk of PTB and pre-pregnancy BMI was determined in women pregnant with twins between 2004 and 2014. Pre-pregnancy BMI values were divided into three groups (underweight/normal/overweight and obese). PTB was classified as spontaneous PTB (following preterm premature rupture of membranes, preterm labor, or cervical insufficiency) or medically indicated PTB (cesarean section or induction of labor because of maternal/fetal indications).

RESULTS

A total of 1,959 women were included in the analysis, and the percentages of total PTB and spontaneous PTB were 13.1% and 9.3%. The percentages of total PTB and spontaneous PTB in three groups were 14.1%, 11.9%, 16.3%, respectively, and 11.0%, 8.0%, 12.5% (P < 0.05 between normal and overweight/obese women). The risks of total and spontaneous PTB in overweight/obese women were higher than those in women with normal weight, even after adjustment for prior history of PTB, age, maternal height, parity, in vitro fertilization-embryo transfer (IVF-ET) (odds ratio [OR], 1.43; 95% confidence interval [CI], 1.01-2.03; OR, 1.58; 95% CI, 1.05-2.36).

CONCLUSION

The risks of both total and spontaneous PTB were significantly greater in the overweight/obese group than in the normal BMI group.

Outcomes of twin pregnancies complicated by gestational diabetes: a meta-analysis of observational studies

OBJECTIVE

Gestational diabetes mellitus (GDM) in singleton pregnancy is associated with large for gestational age neonates and adverse perinatal outcomes; however, the impact of GDM in twin pregnancy is unclear. Thus, the aim of this study is to assess the perinatal outcomes of twin pregnancies complicated by GDM by performing a meta-analysis of observational studies.

STUDY DESIGN

Studies investigating GDM in twin pregnancy were identified through an online search of three databases: Medline, Embase and Web of Science. Selection criteria comprised full paper observational studies (retrospective or prospective) published in English that examined GDM in twin pregnancy compared with non-GDM twin pregnancy and reported on birth weight and/or adverse perinatal outcomes. Random-effects models with inverse-variance weighting were used to calculate standardized mean differences and unadjusted odds ratios. Sensitivity analyses were carried out to determine the impact of possible maternal confounders (body mass index and age) and GDM diagnostic criteria on perinatal outcomes.

RESULTS

Thirteen observational studies were included. GDM twins were born at the same gestation as non-GDM twins, with marginally lower birth weight. There was no difference in the incidence of large or small for gestational age neonates. Although there was no correlation between GDM in twin pregnancy and respiratory distress, neonatal hypoglycemic or low Apgar score, GDM twins had a higher rate of neonatal intensive care unit admission (OR 1.49; 95% confidence interval: 1.10, 2.02; P<0.01).

CONCLUSION

Identification and subsequent treatment of GDM in twin pregnancy demonstrates a similar risk of adverse perinatal outcomes compared with non-GDM twin pregnancies.

Optimal weight gain during twin pregnancy in Japanese women with favorable perinatal outcomes

OBJECTIVE

We examined the optimal weight gain in the healthy Japanese women with favorable perinatal outcomes of (dichorionic) twin pregnancy.

METHODS

We calculated the average weight gain in the women whose height was 150-164 cm with favorable perinatal outcomes of dichorionic twin pregnancy set for this study. The women were categorized to underweight, normal, overweight and obese based on the pre-pregnancy body mass index (BMI) categories according to the Institute of Medicine (IOM) and the World Health Organization (WHO) body mass index (BMI) cutoffs.

RESULTS

The average GWG in the normal-weight women with the favorable perinatal outcomes was 13.9 ± 3.6 kg. It was significantly different from that in the underweight, overweight and obese women according to the both 2 BMI cutoffs by Student's t-test (p < 0.01).

CONCLUSION

There are optimal ranges of weight gain during twin pregnancy based on the BMI classification.

Intrahepatic Cholestasis of Pregnancy in Women With Twin Pregnancy

The aim of the present work was to determine maternal and fetal outcomes of intrahepatic cholestasis of pregnancy (ICP) in twin pregnancies. All twin pregnancies delivered above 28 gestational weeks in West China Second University Hospital from January 2013 to May 2015 were included. Data on maternal demographics and obstetric complications together with fetal outcomes were collected. The risk of adverse maternal and fetal outcomes were determined in relation to ICP by crude odds ratios (OR) and adjusted ORs (aOR) with 95% confidence intervals (CI). Subgroup analysis concentrated on the effect of assisted reproductive technology (ART), ICP severity, and onset time. A total of 1,472 twin pregnancies were included, of which 362 were cholestasis patients and 677 were conceived by ART. Higher rates of preeclampsia (aOR 1.96; 95% CI 1.35, 2.85), meconium-stained amniotic fluid (aOR 3.10; 95% CI 2.10, 4.61), and preterm deliveries (aOR 3.20; 95% CI 2.35, 4.37) were observed in ICP patients. Subgroup analysis revealed higher incidences of adverse outcomes in severe and early onset ICP groups. In conclusion, adverse maternal and fetal outcomes were strongly associated with ICP in twin patients. Active management and close antenatal monitoring are needed, especially in the early onset and severe groups.

The association between maternal height and pregnancy outcomes in twin gestations

OBJECTIVE

We sought to assess the association between maternal height and the risk of preterm birth, fetal growth restriction and mode of delivery in twin gestations.

STUDY DESIGN

Cohort study of patients with twin pregnancies delivered from 2005 to 2014. We compared pregnancy outcomes between patients of short stature ≤159 cm to those of normal stature ≥160 cm. Patients with monoamniotic twins and major fetal anomalies were excluded. Pearson's correlation, Chi-square and Student's t-test were used as appropriate.

RESULTS

Six hundred and sixty-six patients were included, 159 (23.9%) of whom had short stature (mean height 155.8 ± 2.5 cm) and 507 (76.1%) of whom had normal stature (mean height 167.2 ± 5.5 cm). There were no differences in outcomes between the groups in regards to preterm birth, gestational age (GA) at delivery, birth weight of either twin, preeclampsia, gestational diabetes or cesarean section rate. Results were similar when the groups were stratified by parity. As a continuous variable, maternal height did not correlate with GA at delivery (p= 0.388), cesarean delivery (p = 0.522) nor the birth weight of the larger (p = 0.206) or smaller (p = 0.307) twin.

CONCLUSION

In twin pregnancies, maternal short stature is not associated with preterm birth, fetal growth restriction or cesarean section rate. This suggests that although anthropometric measurements have long been used to counsel patients in regards to outcomes, patients of short stature should be reassured that their height does not appear to lead to adverse twin pregnancy outcomes.

Effects of Exercise During Pregnancy on Maternal Heart Rate and Heart Rate Variability

BACKGROUND

Pregnancy is associated with an increased sympathetic state, which can be exacerbated by gestational conditions. Research has shown that exercise during pregnancy lowers heart rate (HR) and can attenuate the symptoms of gestational conditions associated with increased sympathetic control. However, changes in maternal heart autonomic function in response to exercise have not been reported across multiple time points during pregnancy. This analysis is designed to address this gap.

OBJECTIVE

To determine if exercise throughout gestation improves maternal cardiac autonomic nervous system functioning, as evidenced by decreased HR and increased heart rate variability (HRV) indices.

DESIGN

Case control study.

SETTING

Academic medical institution.

PARTICIPANTS

A total of 56 women with healthy, singleton, low-risk pregnancies.

METHODS

Participants were asked to complete 3 resting 18-minute HRV recordings at 28, 32, and 36 weeks' gestation, along with a physical activity questionnaire.

MAIN OUTCOME MEASURES

HRV indices were calculated for time (R peak to R peak interval standard deviation and root mean squared of successive differences) and frequency (very low, low, and high frequency) domain measures. The differences between groups were compared for HRV indices at 28, 32, and 36 weeks.

RESULTS

Resting HR was significantly lower in the exercise group at 28 weeks (P < .01) compared with the control group. The exercise group had significantly (P < .05) increased measures of resting HRV time domain measures at 28, 32, and 36 weeks' gestation compared with the control group. Resting HRV power was significantly increased (P < .05) in all frequency domain measures at 32 weeks in the exercise group relative to the control group. No differences occurred in sympathovagal balance (low frequency/high frequency ratio) between groups.

CONCLUSION

Exercise throughout pregnancy can significantly improve cardiac autonomic control. More research is needed to determine if this adaptation to exercise may reduce the risk of adverse outcomes associated with gestational conditions with poor autonomic control, such as diabetes, hypertension, pre-eclampsia, and excessive weight gain.

Relationship between maternal obesity and prenatal, metabolic syndrome, obstetrical and perinatal complications of pregnancy in Indiana, 2008-2010

BACKGROUND

Obesity is a serious medical condition affecting more than 30% of Indiana, and 25% of Unites States pregnant women. Obesity is related to maternal complications, and significantly impacts the health of pregnant women. The objective of this study was to describe the relationship between maternal complications and pre-pregnancy maternal weight.

METHODS

Using logistic regression models, we analyzed 2008 to 2010 birth certificate data, for 255,773 live births abstracted from the Indiana Vital Statistics registry. We examined the risk of reproductive factors, obstetrical complications and perinatal (intrapartum) complications for underweight, healthy weight, overweight and obese women for this population.

RESULTS

Women who received prenatal care were more likely to be obese [adjusted odds ratio (AOR) = 1.82 (1.56-2.13)]. While women with parity of zero (0) were less likely to be obese [AOR = 0.89, 95% CI (0.86-0.91)]. Women giving birth to twins [AOR = 1.25, 95% CI (1.17- 1.33)], women delivering by Caesarian section [AOR = 2.31, 95% CI ( 2.26-2.37)], and women who previously had a Caesarian section [AOR = 1.95, 95% CI (1.88-2.02)] were more likely to be obese. There was evidence of metabolic like complication in this population, due to obesity. Obesity was significantly associated with obstetrical conditions of the metabolic syndrome, including pre-pregnancy diabetes, gestational diabetes, pre-pregnancy hypertension, pregnancy-induced hypertension and eclampsia [AOR = 5.12, 95% CI (4.47-5.85); AOR = 3.87, 95% CI (3.68-4.08); AOR = 7.66, 95% CI (6.77-8.65); AOR = 3.23, 95% CI (3.07-3.39); and AOR = 1.77, 95% CI (1.31-2.40), respectively. Maternal obesity modestly increased the risk of induction, epidural, post-delivery bleeding, and prolonged labor [AOR = 1.26, 95% CI (1.23-1.29); AOR = 1.15, 95% CI (1.13-1.18); AOR = 1.20, 95% CI (1.12-1.28); and AOR = 1.44, 95% CI (1.30-1.61)], respectively. Obese women were less likely to have blood transfusions [AOR = .74, 95% CI (0.58-96)], vaginal tears [AOR = 0.51, 95% CI (0.44-0.59)], or infections [AOR = 86, 95% CI (0.80-0.93)].

CONCLUSIONS

Our results suggest that maternal obesity in Indiana, like other populations in the USA, is associated with high risks of maternal complications for pregnant women. Pre-pregnancy obesity prevention efforts should focus on targeting children, adolescent and young women, if the goal to reduce the risk of maternal complications related to obesity, is to be reached.

Prepregnancy body mass index is an independent risk factor for gestational hypertension, gestational diabetes, preterm labor, and small- and large-for-gestational-age infants

OBJECTIVE

We examined if prepregnancy body mass index (BMI) is a risk factor for gestational hypertension, gestational diabetes, preterm labor, and small-for-gestational-age (SGA) and large-for-gestational-age (LGA) infants with consideration of gestational weight gain, to document the importance of preconception versus prenatal stage.

METHODS

We used the data of 219 868 women from 2004 to 2011 Pregnancy Risk Assessment Monitoring System (PRAMS). Multivariate logistic regression analyses were performed to examine the effect of prepregnancy BMI for gestational hypertension, gestational diabetes, preterm labor, and SGA and LGA infants with consideration of gestational weight gain.

RESULTS

Regardless of gestational weight gain, women with obese prepregnancy BMI (≥30 kg/m(2)) had increased odds of gestational hypertension (adjusted odds ratios (AOR) = 2.91; 95% CI = 2.76-3.07), gestational diabetes (2.78; 2.60-2.96), and LGA (1.87; 1.76-1.99) compared to women with normal prepregnancy BMI (18.5-24.9 kg/m(2)). Women with underweight prepregnancy BMI (<18.5 kg/m(2)) had increased odds of preterm labor (1.25; 1.16-1.36) and SGA infants (1.36; 1.25-1.49), but decreased odds of LGA infants (0.72; 0.61-0.85) in reference to women with normal prepregnancy BMI (18.5-24.9 kg/m(2)).

CONCLUSIONS

Regardless of adequacy of gestational weight gain, the risk of gestational hypertension, gestational diabetes, and LGA infants increases with obese prepregnancy BMI, whereas that of preterm labor and SGA infants increases with underweight prepregnancy BMI. Preconception care of reproductive aged women is as important as prenatal care to lower the risk of gestational hypertension, gestational diabetes, preterm labor, and SGA and LGA infants.