The impact of maternal prepregnancy impaired fasting glucose on preterm birth and large for gestational age: a large population-based cohort study

Effectiveness and safety of consecutive single embryo transfer compared to double embryo transfer: results from the UK HFEA registry

STUDY QUESTION

How does two-consecutive single embryo transfer (2xSET) affect reproductive outcomes of IVF and ICSI compared to double embryo transfer (DET)?

SUMMARY ANSWER

Two-consecutive SET may provide greater or comparable live birth rate (LBR); with lower multiple birth, preterm birth, and pregnancy loss or neonatal death rates compared to DET.

WHAT IS KNOWN ALREADY

Elective SET in IVF/ICSI is widely encouraged over DET to minimize the risk of multiple births and associated morbidities. Despite this, multiple birth rates following IVF remain higher than the 10% target across Europe and the USA. Currently, the majority of evidence regarding SET and DET is based on various studies assessing outcomes such as LBR per treatment cycle, as opposed to per oocyte retrieval. As such, the representation of SET is mostly unfavourable. Analysis of cumulative LBR following the transfer of two embryos over consecutive cycles, rather than in one transfer event (DET) is more effective at distinguishing the two methods and will therefore provide more valuable information relevant to clinical practice.

STUDY DESIGN, SIZE, DURATION

This retrospective cohort study was conducted using Human Fertilisation and Embryology Authority (HFEA) register data, which encompasses national data from all IVF clinics in the UK. All women who underwent their first oocyte retrieval and IVF or ICSI treatment cycle with subsequent SET, DET, or 2xSET between 2010 and 2019 using blastocyst embryos were included (N = 71 807).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The rate of live birth, liveborn baby rate, multiple birth, preterm birth, and pregnancy loss or neonatal death was compared between SET, DET, and 2xSET IVF/ICSI pregnancies using blastocyst-stage embryos, where data were stratified by maternal age. Data analysis was conducted in RStudio v4.2, alpha equals 0.05.

MAIN RESULTS AND THE ROLE OF CHANCE

Blastocyst-stage 2xSET achieved a greater median LBR of 0.47 (interquartile range [IQR] 0.13) than SET, 0.41 (IQR 0.13), and DET, 0.38 (IQR 0.13) (P < 0.05). Using SET as the reference standard, 2xSET was associated with a significantly lower odds of multiple births compared to DET ((odds ratio [OR] 6.87, 95% CI 6.14-7.68) vs 28.20, 95% CI 25.20-31.57). The odds of preterm birth were also lower following 2xSET (OR 1.11, 95% CI 1.06-1.15) compared to DET (OR 2.80, 95% CI 2.67-2.94). Similarly, the odds of pregnancy loss or neonatal death were lower following 2xSET (OR 1.14, 95% CI 1.08-1.21) compared to DET (OR 2.11, 95% CI 1.98-2.24). LBR was consistently higher following 2xSET than DET and SET in women aged 39 years and under (P < 0.05). However, results were comparable in women over 39 years (P > 0.05). Across all age groups, DET pregnancies had the highest multiple birth rate (P < 0.05). In women aged 39 years and under, DET was associated with the highest preterm birth rate (P < 0.05), whereas the rate was comparable across cohorts in women over 39 (P > 0.05). Moreover, pregnancy loss and neonatal death rates were highest following DET in women aged 37 years and under (P < 0.05), and comparable to SET and 2xSET in women over 37 years (P > 0.05).

LIMITATIONS, REASONS FOR CAUTION

Certain confounders are not recorded within HFEA registry data, including patient BMI, evaluation of embryo quality, and endometrial thickness at embryo transfer. Consequently, while our analysis identifies broad trends in embryo transfer success and morbidity, results may differ within certain patient populations.

WIDER IMPLICATIONS OF THE FINDINGS

Blastocyst-stage 2xSET may provide greater LBR in women aged 39 years and under, and comparable LBR in women over 39 years old, with overall lower multiple birth and morbidity than DET. 2xSET should be considered first-line among certain patient cohorts, including women with advanced maternal age to improve reproductive outcomes and reduce the risk of morbidity following ART.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used for this study. None of the authors has any conflicts of interest.

TRIAL REGISTRATION NUMBER

This cohort study did not require registration. Following consultation with the Institutional Review Board at Imperial College London, ethical approval was not deemed necessary.

Pre-pregnancy intrauterine device use is associated with a reduced risk of subsequent preterm birth: a large population-based cohort study

BACKGROUND

The effect of pre-pregnancy intrauterine device (IUD) use on subsequent preterm birth (PTB) remains unclear. We aim to investigate the association between IUD use before pregnancy and subsequent PTB.

METHODS

A total of 240,437 women who participated in the National Free Preconception Health Examination Project (NFPHEP) in Yunnan from 2013 to 2019 were included in the study. All study participants were classified into three groups according to their use of pre-pregnancy contraceptive methods: non-method users, IUD users, and other method users. We used a multivariable Poisson regression model to investigate the association between the use of an IUD before pregnancy and subsequent PTB. Further models analyzed the multiplicative and additive interactions between pre-pregnancy IUD use and county deprivation.

RESULTS

Of all the participants, 45,374 (18.9%) used IUDs before pregnancy, 39,414 (16.4%) used other contraceptive methods, and 155,649 (64.7%) were non-method users. The overall PTB rate was 5.30% (95% confidence interval [95% CI], 5.20-5.38%), and women in the IUD group had a significantly lower PTB rate (4.86%, 95% CI 4.66-5.06%) than women in the non-method (5.42%, 95% CI 5.31-5.53%) and other method groups (5.33%, 95% CI 5.11-5.56%). IUD use before pregnancy was associated with a reduced risk of subsequent PTB (model 1: adjusted relative risk [aRR] 0.84, 95% CI 0.80 to 0.89; model 2: aRR 0.84, 95% CI 0.79 to 0.90). In counties with a normal level of development, IUD users had a 30% lower risk of subsequent PTB than non-users (aRR 0.70, 95% CI 0.63 to 0.78). Compared with non-IUD users (incuding non-method and other method users) from the least developed counties, those from counties with a normal level of socioeconomic development had the lowest risk of subsequent PTB (aRR 0.71, 0.62 to 0.82). The additive interaction between pre-pregnancy IUD use and low level of county development was statistically significant (relative excess risk due to interaction [RERI] -0.27, -0.41 to -0.14).

CONCLUSION

Pre-pregnancy IUD use is associated with a reduced risk of subsequent PTB. Pre-pregnancy IUD users in counties with a normal level of development were associated with a lower risk of subsequent PTB than their counterparts in the least developed countries.

A new classification method for gestational diabetes mellitus: a study on the relationship between abnormal blood glucose values at different time points in oral glucose tolerance test and adverse maternal and neonatal outcomes in pregnant women with gestational diabetes mellitus

Background

Gestational diabetes mellitus (GDM) can lead to various adverse pregnancy outcomes for both mothers and infants, including gestational hypertension, premature rupture of membranes, preterm birth, macrosomia, large for gestational age (LGA) infants, and neonatal hypoglycemia. Previous studies have mainly focused on the overall risk of GDM for adverse maternal and neonatal outcomes, but there has been limited research specifically investigating the relationship between different patterns of abnormal oral glucose tolerance test (OGTT) results and adverse maternal and neonatal outcomes.

Objective

The study aimed to analyze the maternal and neonatal outcomes among GDM women with different OGTT patterns and to explore a new classification method capable of stratifying GDM into high-risk (GDM-HR) and low-risk subtypes based on OGTT results.

Study Design

We conducted a retrospective cohort study at the Women's Hospital, School of Medicine, Zhejiang University, spanning from November 1, 2015, to April 30, 2018. During the study period, a total of 3268 cases of GDM were enrolled. Based on the results of the OGTT, these GDM cases were classified into 7 subtypes, and the composition ratio of each subtype and their maternal and neonatal outcomes were analyzed. Innovatively, we proposed to categorize GDM-HR (characterized by elevated fasting blood glucose [FBG] levels, including T0, T0+1, T0+2, and T0+1+2) and low-risk GDM (GDM-LR, without elevated FBG, including T1, T2, and T1+2) and compared the maternal and neonatal outcomes between the two subtypes.

Results

(1) In this cohort of 3268 GDM cases, the composition ratios of the 7 GDM subtypes were as follows: T0 (7.9%, n=260), T1 (24.2%, n=791), T2 (27.4%, n=897), T0+1 (5.4%, n=175), T0+2 (1.7%, n=56), T1+2 (26.2%, n=855), and T0+1+2 (7.2%, n=234). (2) GDM subtypes with elevated FBG levels (GDM-HR) exhibit more severe adverse prognostic outcomes compared to those without elevated FBG levels (GDM-LR). (3) Multiple logistic regression analysis revealed that compared to the GDM-LR group, the GDM-HR group showed increased fetal birth weight (by approximately 150 grams), and had higher rates of cesarean section (adjusted odds ratio [aOR]: 1.45, 95% confidence interval [CI]: 1.19-1.76), hypertensive disorders of pregnancy (aOR: 1.78, 95% CI: 1.35-2.35), preterm birth (aOR: 1.59, 95% CI: 1.17-2.16), macrosomia (aOR: 2.66, 95% CI: 2.07-3.43), LGA infants (aOR: 2.46, 95% CI: 2.05-2.97), and neonatal hypoglycemia (aOR: 2.00, 95% CI: 1.37-2.91). Partial correlation analysis shows a positive correlation between fetal birth weight and FBG levels, with r=0.222, P<.001. Multiple linear regression indicates that for every 1 mmol/L increase in FBG, the fetal weight is estimated to increase by approximately 188 grams.

Conclusion

The composition ratio of GDM subtypes with elevated FBG (GDM-HR) is relatively low within GDM cases, yet it presents with a higher risk of adverse outcomes compared to subtypes without elevated FBG (GDM-LR), warranting increased attention from obstetricians. Applying this new classification method in clinical practice enables better differentiation and individualized management of GDM.

Gestational diabetes complicated with preterm birth: a retrospective cohort study

OBJECTIVE

To delineate the clinical characteristics of preterm birth (PTB) in the context of gestational diabetes mellitus (GDM).

METHODS

A retrospective cohort study was conducted, including 14,314 pregnant women with GDM who delivered at Fujian Provincial Maternity and Children's Hospital from January 1, 2018, to December 31, 2021. PTB was stratified into late PTB (34-36 weeks of gestation) and early PTB (< 34 weeks) and pregnancy complications were analyzed.

RESULTS

Compared to the term birth (TB) cohort, a higher prevalence of premature rupture of membranes, hypertensive diseases of pregnancy (HDP), intrahepatic cholestasis of pregnancy (ICP), anemia and cervical insufficiency was observed in the PTB cohort. Notably, early PTB increased the incidence of HDP, ICP, anemia and cervical insufficiency compared to late PTB. In the early stages of pregnancy, early PTB was characterized by elevated triglyceride (TG) levels and decreased high-density lipoprotein cholesterol (HDL-C) levels compared to late PTB. In the late pregnancy stages, early PTB was associated with increased white blood cell (WBC) and neutrophil counts. No disparities were observed in 75 g oral glucose tolerance test (OGTT) between early and late PTB.

CONCLUSION

Enhanced surveillance and management of GDM, particularly in the presence of HDP, ICP and anemia, are imperative to mitigate the risk of PTB. The lipid profile may serve as a predictive tool for early PTB in the early stages of pregnancy, warranting further studies.

Identification of key metabolism-related genes and pathways in spontaneous preterm birth: combining bioinformatic analysis and machine learning

Background

Spontaneous preterm birth (sPTB) is a global disease that is a leading cause of death in neonates and children younger than 5 years of age. However, the etiology of sPTB remains poorly understood. Recent evidence has shown a strong association between metabolic disorders and sPTB. To determine the metabolic alterations in sPTB patients, we used various bioinformatics methods to analyze the abnormal changes in metabolic pathways in the preterm placenta via existing datasets.

Methods

In this study, we integrated two datasets (GSE203507 and GSE174415) from the NCBI GEO database for the following analysis. We utilized the "Deseq2" R package and WGCNA for differentially expressed genes (DEGs) analysis; the identified DEGs were subsequently compared with metabolism-related genes. To identify the altered metabolism-related pathways and hub genes in sPTB patients, we performed multiple functional enrichment analysis and applied three machine learning algorithms, LASSO, SVM-RFE, and RF, with the hub genes that were verified by immunohistochemistry. Additionally, we conducted single-sample gene set enrichment analysis to assess immune infiltration in the placenta.

Results

We identified 228 sPTB-related DEGs that were enriched in pathways such as arachidonic acid and glutathione metabolism. A total of 3 metabolism-related hub genes, namely, ANPEP, CKMT1B, and PLA2G4A, were identified and validated in external datasets and experiments. A nomogram model was developed and evaluated with 3 hub genes; the model could reliably distinguish sPTB patients and term labor patients with an area under the curve (AUC) > 0.75 for both the training and validation sets. Immune infiltration analysis revealed immune dysregulation in sPTB patients.

Conclusion

Three potential hub genes that influence the occurrence of sPTB through shadow participation in placental metabolism were identified; these results provide a new perspective for the development and targeting of treatments for sPTB.

Despite treatment, HbA1c ≥ 37 mmol/mol in the first trimester is associated with premature delivery among South Asian women with gestational diabetes mellitus: a retrospective cohort study

PURPOSE

To examine the effects of first-trimester HbA1c (HbA1c-FT) ≥ 37 mmol/mol on preterm birth (PTB) and large-for-gestational-age (LGA) babies in a retrospective cohort of South Asian pregnant women with gestational diabetes (GDM).

METHODS

The cohort (n = 686) was separated into two groups based on HbA1c-FT values: Group A (n = 97) and Group B (n = 589), with values of 37-46 mmol/mol (5.5-6.4%) and < 37 mmol/mol (5.5%), respectively. HbA1c-FT's independent influence on PTB and LGA babies was examined using multivariable logistic regression in groups A and B women. The reference group (Group C) included 2031 non-GDM women with HbA1c-FT < 37 mmol/mol (< 5.5%). The effects of HbA1c-FT on PTB and LGA babies in obese women in Groups A, B, and C (designated as A-ob, B-ob, and C-ob, respectively) were re-analyzed using multivariable logistic regression.

RESULTS

Group A GDM women with greater HbA1c-FT had a higher risk for PTB (aOR:1.86, 95% CI:1.10-3.14) but not LGA babies (aOR:1.13, 95%: 0.70-1.83). The risk of PTB was higher for obese women in Group A-ob: aOR 3.28 [95% CI 1.68-6.39]. However, GDM women with normal HbA1c-FT exhibited no elevated risk for PTB: Groups B and B-ob had aORs of 1.30 (95% CI 0.86-1.98) and 1.28 (95% CI 0.88-1.85) respectively.

CONCLUSIONS

South Asian GDM women with prediabetic HbA1c FT; 37-46 mmol/mol (5.5-6.4%) are more likely to deliver preterm babies despite treatment, while the risk for LGA babies was the same as non-GDM women.

Association of maternal preconception blood pressure with preterm birth: a population-based cohort study

The association between maternal preconception blood pressure (BP) and preterm birth (PTB) is still unclear. The purpose of this study was to investigate the association between maternal preconception BP and PTB. This population-based cohort study included 715 984 Chinese women aged 20-49 years who participated in the National Free Preconception Health Examination Project and successfully had a singleton livebirth during 2014-2019 in Guangdong Province, China. Maternal preconception BP were measured by trained health workers. Multivariate logistic regression models and restricted cubic spline regressions were used to examine the association and dose-response relationship between maternal preconception BP and PTB, respectively. Maternal preconception hypertension was associated with the increased risk of PTB (adjusted odds ratios (aOR): 1.24; 95% CI: 1.14-1.34). Compared to women with normal preconception BP, the aORs for PTB were 1.09 (95% CI: 1.06-1.12), 1.24 (95% CI: 1.13-1.36), and 1.43 (95% CI: 1.15-1.79) for women with preconception elevated BP (120-139/ 80-89 mmHg, stage-1 hypertension (140-159/ 90-99 mmHg, and stage-2 hypertension (160-179/100-109 mmHg), respectively. According to the 2017 American College of Cardiology/American Heart Association criteria, maternal preconception elevated BP and hypertension were also significantly associated with an increased risk of PTB. Preconception systolic and diastolic BP showed a U-shaped (χ2 = 40.54; nonlinear P < 0.001) and linear (χ2 = 6.62; nonlinear P = 0.085) dose-response relationship with PTB, respectively. The association was modified by maternal age and preconception body mass index. These findings identify maternal preconception elevated BP and hypertension as a modifiable risk factor for PTB, providing evidence for future research studies, public health and clinical interventions.

Prepregnancy Glucose Levels Within Normal Range and Its Impact on Obstetric Complications in Subsequent Pregnancy: A Population Cohort Study

BACKGROUND

We sought to identify the influence of prepregnancy glucose levels on obstetric complications in subsequent pregnancy.

METHODS

Women in Republic of Korea who had given birth between January 1st, 2007 and December 31st, 2010 were enrolled. The database of the Health Insurance Review and Assessment Service and data from a national health screening program for infants and children were used. Subjects were divided into seven groups according to their fasting glucose levels.

RESULTS

59,619 women were included for analysis, and 10.4%, 13.7%, 19.1%, 21.5%, 16.0%, 11.6%, and 7.5% women had glucose levels of < 75, 75-79, 80-84, 85-89, 90-94, 95-100 and > 100 mg/dL. Each 5 mg/dL increase in prepregnancy fasting glucose levels was associated with increased risk of gestational diabetes and macrosomia in subsequent pregnancy. Adjusted risk ratio for gestational diabetes per standard deviation prepregnancy glucose > 100 mg/dL was 2.015 (95% confidence interval, 1.649-2.462) and for macrosomia an adjusted risk ratio 1.389 (95% confidence interval, 1.147-1.682).

CONCLUSION

Higher prepregnancy glucose level within normal range was related to gestational diabetes and macrosomia in following pregnancy. Our results may aid in the identification of women at future risk of obstetric complications and may guide to stratify women into normal and intensified care.

TWEETABLE ABSTRACT

Higher prepregnancy glucose in normal range is associated with gestational diabetes and macrosomia.

Associations between pregnancy glucose measurements and risk of preterm birth: a retrospective cohort study of commercially insured women in the United States from 2003 to 2021

PURPOSE

To investigate associations between glucose measurements during pregnancy and risk of preterm birth (PTB).

METHODS

Retrospective cohort study of commercially insured women with singleton live births in the United States from 2003 to 2021 using longitudinal medical claims, socioeconomic data, and eight glucose results from different fasting and post-load tests performed between 24 and 28 weeks of gestation for gestational diabetes screening. Risk ratios of PTB (<37 weeks) were estimated via Poisson regression for z-standardized glucose measures. Non-linear relationships for continuous glucose measures were examined via generalized additive models.

RESULTS

Elevations in all eight glucose measures were associated with increased risk (adjusted risk ratio point estimates: 1.05-1.19) of PTB for 196,377 women with non-fasting 50-g glucose challenge test (one glucose result), 31,522 women with complete 100-g, 3-hour fasting oral glucose tolerance test (OGTT) results (four glucose results), and 10,978 women with complete 75-g, 2-hour fasting OGTT results (three glucose results). Associations were consistent after adjusting for and stratifying by sociodemographic and clinical factors. Substantial non-linear relationships (U-, J-, and S-shaped) were observed between several glucose measurements and PTB.

CONCLUSIONS

Elevations in various glucose measures were linearly and non-linearly associated with increased PTB risk, even before diagnostic thresholds for gestational diabetes.

Associations Between Preconception Glycemia and Preterm Birth: The Potential Role of Health Care Access and Utilization

Background: Preconception diabetes is strongly associated with adverse birth outcomes. Less is known about the effects of elevated glycemia at levels below clinical cutoffs for diabetes. In this study, we estimated associations between preconception diabetes, prediabetes, and hemoglobin A1c (HbA1c) on the risk of preterm birth, and evaluated whether associations were modified by access to or utilization of health care services. Materials and Methods: We used data from Add Health, a US prospective cohort study with five study waves to date. At Wave IV (ages 24-32), glucose and HbA1c were measured. At Wave V (ages 32-42), women with a live birth reported whether the baby was born preterm. The analytic sample size was 1989. Results: The prevalence of preterm birth was 13%. Before pregnancy, 6.9% of women had diabetes, 23.7% had prediabetes, and 69.4% were normoglycemic. Compared to the normoglycemic group, women with diabetes had 2.1 (confidence interval [95% CI]: 1.5-2.9) times the risk of preterm birth, while women with prediabetes had 1.3 (95% CI: 1.0, 1.7) times the risk of preterm birth. There was a nonlinear relationship between HbA1c and preterm birth such that risk of preterm birth emerged after HbA1c = 5.7%, a standard cutoff for prediabetes. The excess risks of preterm birth associated with elevated HbA1c were four to five times larger among women who reported unstable health care coverage and among women who used the emergency room as usual source of care. Conclusion: Our findings replicate prior research showing strong associations between preconception diabetes and preterm birth, adding that prediabetes is also associated with higher risk. Policies and interventions to enhance access and utilization of health care among women before pregnancy should be examined.

PM2.5 exposure increases the risk of preterm birth in pre-pregnancy impaired fasting glucose women: A cohort study in a Southern province of China

Previous studies have indicated maternal exposure to particles with aerodynamic diameter <2.5 μm (PM_2.5) is associated with preterm birth (PTB). However, no study has investigated this effect in pre-pregnancy impaired fasting glucose (IFG) women. This study aimed to differentiate the effects of maternal PM_2.5 exposure on PTB between pre-pregnancy IFG and normoglycemia women, and to further identify the susceptible window. This cohort study was conducted between January 2014 and December 2017 in 21 Chinese cities. All the recruited women received pre-pregnancy fasting serum glucose (FSG) tests and were followed up for their delivery outcomes. The PM_2.5 exposures were estimated by the daily air pollution concentrations of the nearby monitors. Women with FSG below 7.0 mmol/L were included in the analysis. We employed the Cox proportional hazards models to examine whether PM_2.5 exposure was associated with PTB. 237957 women were included and 7055 (3.0%) of them were pre-pregnancy IFG. During the entire pregnancy, we found 24.1% (HR = 1.241; 95% CI: 1.069, 1.439), 61.8% (HR = 1.618; 95% CI: 1.311, 1.997) and 18.6% (HR = 1.186; 95% CI: 1.004, 1.402) of increases in risk for all PTB, early PTB (20-33 gestational weeks) and late PTB (34-36 gestational weeks) among the pre-pregnancy IFG women, and 15.9% (HR = 1.159; 95% CI: 1.127, 1.192), 33.9% (HR = 1.339; 95% CI: 1.255, 1.430) and 13.2% (HR = 1.132; 95% CI: 1.098, 1.168) of increases in risk for all PTB, early PTB and late PTB among the normoglycemia women, with each 10 μg/m³ increment of PM_2.5 exposure, respectively. Furthermore, PM_2.5 exposure had the strongest effect on all PTB during trimester 1 (0-12 gestational weeks) among the pre-pregnancy IFG women, compared with the less strong effect during trimester 1 among the normoglycemia women. In conclusion, pre-pregnancy IFG increases the risk of PTB attributed to PM_2.5, especially during trimester 1. Moreover, the effects of PM_2.5 are greater on early PTB than late PTB for both pre-pregnancy IFG and normoglycemia women.

Association between maternal pregestational glucose level and adverse pregnancy outcomes: a population-based retrospective cohort study

OBJECTIVE

To investigate the association between maternal pregestational blood glucose level and adverse pregnancy outcomes.

DESIGN

Retrospective cohort study.

SETTING

This study was conducted in the Chongqing Municipality of China between April 2010 and December 2016.

PARTICIPANTS

A total of 60 222 women (60 360 pregnancies) from all 39 counties of Chongqing who participated in the National Free Preconception Health Examination Project and had pregnancy outcomes were included.

PRIMARY OUTCOME MEASURES

Adverse pregnancy outcomes included spontaneous abortion, induced abortion or labour due to medical reasons, stillbirth, preterm birth (PTB), macrosomia, large for gestational age, low birth weight (LBW) and small for gestational age.

RESULTS

Of the 60 360 pregnancies, rates of hypoglycaemic, normoglycaemia, impaired fasting glycaemia (IFG) and diabetic hyperglycaemic before conception were 5.06%, 89.30%, 4.59% and 1.05%, respectively. Compared with women with normoglycaemia, women with pregestational glucose at the diabetic level (≥7.0 mmol/L) might have a higher rate of macrosomia (6.18% vs 4.16%), whereas pregestational IFG seemed to be associated with reduced risks of many adverse outcomes, including spontaneous abortion, induced abortion due to medical reasons, PTB and LBW. After adjusting for potential confounders, pregestational diabetic hyperglycaemic was remained to be significantly associated with an increased risk of macrosomia (adjusted risk ratio 1.49, 95% CI 1.07 to 2.09). Abnormal maternal glucose levels before pregnancy (either hypoglycaemic or hyperglycaemic) seemed to have no significant negative effect on spontaneous abortion or induced abortion due to medical reasons.

CONCLUSION

Although without overt diabetes mellitus, women with once diabetic fasting glucose level during their preconception examinations could be associated with an increased risk for macrosomia. Uniform guidelines are needed for maternal blood glucose management during pre-pregnancy care to improve pregnancy outcomes.

History of IUD utilization and the risk of preterm birth: a cohort study

OBJECTIVE

To explore whether a history of IUD use could increase the risk of subsequent preterm birth.

METHODS

We performed a cohort study of 24,496 multipara aged 19-48 years in Dongguan City. Each subject was followed up for 1 year, and 12,508 women obtained pregnancy outcomes. They were divided into 2 groups: 2130 subjects with IUD use history (exposure group), and 10,378 subjects without IUD use history (control group). The exposure group will remove the IUD before pregnancy. The primary outcomes were preterm birth (less than 37 weeks of gestation) and early preterm birth (less than 34 weeks of gestation). We used log-binomial regression to estimate adjusted risk ratios (aRR) of preterm birth and early preterm birth for women with a history of IUD. According to the different adjusted baseline data, three regression models were established, and the propensity matching score method was also used to verify the stability of the results.

RESULTS

The delivery rate of women with IUD history was 51.24%, and that of women without IUD was 51.03% (² = 0.063, P = 0.802). Six hundred and eighty-five women had preterm birth (5.48%, 95% CI 5.08-5.88) and 133 women had early preterm birth (1.06%, 95% CI 0.83-1.24). Compared with the control group, the incidence of preterm birth and early preterm birth in the exposure group were significantly lower. The results are stable in all four models. Subgroup analysis also supported the result. This study also found that the longer the women used IUD before pregnancy, the younger the age of first using IUD, and the shorter the time from condom removal to pregnancy, the lower the incidence of premature birth.

CONCLUSION

The women with a history of IUD use are less likely to have premature birth after the IUD is removed. More prospective studies are needed to confirm it.

Association of maternal pre-pregnancy low or increased body mass index with adverse pregnancy outcomes

This study investigated the association between pre-pregnancy body mass index (BMI) and adverse pregnancy outcomes among women participated in the National Free Preconception Health Examination Project in Guangdong Province, China, and explored these associations according to maternal age. Pre-pregnancy BMI was classified into underweight (BMI < 18.5 kg/m²), healthy weight (18.5–23.9 kg/m²), overweight (24.0–27.9 kg/m²), and obesity (≥ 28.0 kg/m²) according to Chinese criteria. Outcomes were preterm birth (PTB, delivery before 37 weeks of gestation), large for gestational age (LGA, birthweight above the 90th percentile for gestational age by infants’ sex), small for gestational age (SGA, birthweight below the 10th percentile for gestational age by infants’ sex), primary caesarean delivery, shoulder dystocia or birth injury, and stillbirth. Adjusted incidence risk ratios (aIRR) were calculated for underweight, overweight and obesity, respectively. Compared with healthy weight, underweight was associated with increased risk of PTB (aIRR 1.06, 95%CI 1.04–1.09) and SGA (1.23, 1.22–1.26) but inversely associated with LGA (0.83, 0.82–0.85), primary caesarean delivery (0.88, 0.87–0.90) and stillbirth (0.73, 0.53–0.99). Overweight was associated with increased risk of LGA (1.17, 1.14–1.19), primary caesarean delivery (1.18, 1.16–1.20) and stillbirth (1.44, 1.03–2.06), but inversely associated with SGA (0.92, 0.90–0.95) and shoulder dystocia or birth injury (0.86, 0.79–0.93). Obesity was associated with increased risk of PTB (1.12, 1.05–1.20), LGA (1.32, 1.27–1.37), primary caesarean delivery (1.45, 1.40–1.50), but inversely associated with SGA (0.92, 0.87–0.97). The aIRRs for underweight, overweight and obesity in relation to these adverse pregnancy outcomes ranged from 0.65 to 1.52 according to maternal age. In Chinese population, maternal pre-pregnancy BMI was significantly associated with the risk of adverse pregnancy outcomes and the risk differs according to maternal age. Further investigation is warranted to determine whether and how counselling and interventions for women with low or increased BMI before pregnancy can reduce the risk of adverse pregnancy outcomes.

Associations of pre-pregnancy impaired fasting glucose and body mass index among pregnant women without pre-existing diabetes with offspring being large for gestational age and preterm birth: a cohort study in China

INTRODUCTION

Associations of pre-pregnancy impaired fasting glucose (IFG) and body mass index (BMI) with large for gestational age (LGA) and preterm birth (PTB) have been poorly understood. We aimed to investigate the associations of maternal BMI, separately and together with pre-pregnancy IFG, with LGA and PTB in Chinese population. We also aimed to quantify these associations by maternal age.

RESEARCH DESIGN AND METHODS

This was a retrospective cohort study of women from the National Free Preconception Health Examination Project with singleton birth from 121 counties/districts in 21 cities of Guangdong Province, China, from January 1, 2013 to December 31, 2017. Women were included if they did not have pre-existing chronic diseases (diabetes, hypertension, etc). Participants were divided into eight groups according to their BMI (underweight (BMI <18.5 kg/m²), normal weight (18.5-23.9 kg/m²), overweight (24.0-27.9 kg/m²), and obesity (≥28.0 kg/m²)) and pre-pregnancy fasting glucose status (normoglycemia (fasting glucose concentration <6.1 mmol/L) and IFG (6.1-7.0 mmol/L)). Adjusted incidence risk ratios (aIRRs) and 95% CIs of LGA, severe LGA, PTB and early PTB were estimated.

RESULTS

We included 634 030 women. The incidences of LGA, severe LGA, PTB and early PTB for the study population were 7.1%, 2.5%, 5.1% and 1.1%, respectively. Compared with normal weight mothers with normoglycemia, overweight and obese mothers irrespective of IFG had a higher risk of LGA (eg, obesity with IFG aIRR 1.85 (1.60-2.14)) and severe LGA (eg, obesity with IFG 2.19 (1.73-2.79)). The associations of BMI and pre-pregnancy fasting glucose status with LGA were similar found among women of all age groups. Underweight with normoglycemia had 6.0% higher risk of PTB (1.06 (1.03-1.09)) and 8.0% higher risk of early PTB (1.08 (1.02-1.17)), underweight with IFG had 14.0% higher risk of PTB (1.14 (1.02-1.27)), and obese mothers with IFG had 45.0% higher risk of PTB (1.45 (1.18-1.78)). The associations of BMI and pre-pregnancy fasting glucose status with PTB differed by maternal age.

CONCLUSION

Overweight and obesity regardless of IFG were associated with an increased risk of LGA, and these associations were similarly observed among mothers of all age groups. Underweight regardless of IFG, and obesity with IFG were associated with an increased risk of PTB, but the associations differed by maternal age. Findings from this study may have implications for risk assessment and counselling before pregnancy.