37th Week Of Gestation Research Articles

Premaxillary-maxillary suture development in the first trimester : An ultrasound study.

Our study was designed to investigate premaxillary-maxillary suture growth in fetuses from the first trimester of pregnancy using the B‑ultrasound technique in order to determine the suture fusion time. We selected 169 healthy Han singleton pregnancies as subjects. All subjects received routine pregnancy tests and were divided into three groups based on the gestational age of the fetus: group1, the 11th gestational week; group2, the 12th gestational week; and group3, the 13th gestational week. Fetal biometric measurements were recorded during consecutive prenatal ultrasonographic examinations. These measurements included nuchal translucency thickness, crown-rump length, and premaxillary-maxillary length. Intergroup comparisons were performed using analysis of variance (ANOVA). The premaxillary-maxillary suture grows gradually and its measured length at the 11th, 12th and 13th week was 0.54 cm, 0.65 cm, and 0.74 cm, respectively. We observed asignificant linear correlation between the premaxillary-maxillary length and the week of gestation in the first trimester. The growth rate of the maxilla at the 11th, the 12th and the 13th week are significantly different with adescending order of growth rates being week12, week11 and week13, with the 12th week rate being the most rapid. The premaxillary and maxillary growth at 11 and 12 gestational weeks in the first trimester steadily accelerated, peaking at the 12th week. The rate of growth slows down after week 12 which may be associated with the fusion of the premaxillary-maxillary suture.

Vitamin D Supplemental Therapy can Explore the Interplay Circuit between Hypovitaminosis D, High Serum IL-6 and Pregnancy-Associated Morbidities

Objectives: To evaluate the relation between baseline Vitamin D (VD) serum levels and incidence and severity of Pregnancy-Associated Morbidities (PAM). Patients and methods: The study included 386 pregnant women attended at the 6th gestational week and after full clinical and obstetric examination, gave fasting blood samples for estimation of fasting blood glucose (FBG) and ELISA estimation of serum VD, insulin and interleukin-6 (IL-6). Insulin resistance (IR) was determined according to homeostasis model assessment IR (HOMA-IR) score that was considered abnormal at score of ≥ 2. Enrolled women were categorized according to a booking VD level as sufficient (Group A), insufficient (Group B) and deficient (Group C). Women of group C received daily oral VD (1000 IU) supplemental therapy (VD-ST) till delivery. Study outcomes included incidence of PAM and its relation to serum VD levels, and the effect of VD-ST on incidence and severity of PAM. Results: Groups A-C included 86, 130 and 170 women, respectively and 263 women developed 424 PAM. PAM incidence and serum IL-6 levels were significantly higher in group B than other groups. PAM incidence and serum IL-6 levels showed negative significant correlations with serum VD levels. Moreover, PAM incidence showed positive significant correlation with serum IL-6 level. ROC curve analysis defined at booking serum VD as significant specific and serum IL-6 as significant sensitive predictors for PAM development. VD-ST allowed significant reduction of PAM with significant reduction of serum IL-6 and FBG levels and IR. Incidence of PAM was negatively correlated with receiving VD-ST that was found to be significant predictor for decreased PAM incidence. Conclusion: Hypovitaminosis D and high IL-6 serum levels may underlie PAM development. VD-ST improved pregnancy outcome in women with VD deficiency to a level better than in women with insufficient VD levels; thus it is recommended as empirical therapy for pregnant women.

Doppler Indices and Notching Assessment of Uterine Artery Between the 19th and 22nd Week of Pregnancy in the Prediction of Pregnancy Outcome.

The aim of this study was to determine the value of Doppler indices and notching assessment of uterine artery between the 19th and 22nd week of gestation in the prediction of pregnancy outcome such as delivery mode, birth weight, Apgar score, afterbirth pH, fetal presentation, preeclampsia and fetal growth restriction in singleton pregnancy. This is a retrospective cohort study of Doppler ultrasound of the uterine arteries at 19-22 week of gestation in 1,472 women with singleton pregnancies. Patients with bilateral high resistance-index (RI) and pulsatility-index (RI) or with the presence of a notch showed a significantly higher prevalence of small for gestational age (SGA) fetuses and intrauterine growth restriction (IUGR), low Apgar Scores at the 1st and the 5th min, high c-section rate, preterm birth, breech birth, placental insufficiency and placental abruption. The presence of a notch significantly increased the prevalence of severe preeclampsia, HELLP-syndrome and oligohydramnios. Also, patients with a bilateral uterine notching had a higher c-section rate along with higher prevalence of SGA and IUGR at screening time. Uterine artery Doppler waveform analysis as well as the assessment of the presence of a notch in the second trimester can be used as a screening method to identify women who will thereafter develop a severe adverse outcome.

Does Fear of Giving Birth Impact the Self-Efficacy Perceptions of a Pregnant Woman?

Background: The fear of death during delivery develops before pregnancy; it is called "tokophobia". Aim: To compare the self-efficacy perceptions of pregnant women based on the degree of their fear of giving birth and to determine the relationship between the two considerations. Methods: This study was conducted with a descriptive and corelational design between January 2 and October 31, 2014 in a maternity hospital in Eastern Turkey. Women in their 28th–40th gestational week, visiting the hospital were included in the study. Version A of the Wijma delivery expectancy/experience scale and the short version of the birth self-efficacy inventory were used to collect the data. Results: Among the pregnant women with low fear of giving birth, the mean scores were 61.88±13.35 for Wijma and 217.50±40.31 for the self-efficacy scale. For the pregnant women with high fear of giving birth, Wijma scores were 115.98±15.92 and self-efficacy scale was 169.57±44.26. Conclusion: This study emphasize that pregnant women with low fear of giving birth had higher levels of self-efficacy perception compared to those with high fear of giving birth.

Longitudinal association of 25-hydroxyvitamin D with adipokines and markers of glucose metabolism among Brazilian pregnant women.

This study aimed to evaluate the longitudinal association of vitamin D status with glycaemia, insulin, homoeostatic model assessment of insulin resistance, adiponectin and leptin. A prospective cohort with 181 healthy, pregnant Brazilian women was followed at the 5th-13th, 20th-26th and 30th-36th gestational weeks. In this cohort, 25-hydroxyvitamin D (25(OH)D) plasma concentrations were analysed using liquid chromatography-tandem MS. Vitamin D status was categorised as sufficient or insufficient using the Endocrine Society Practice Guidelines (≥75/<75 nmol/l) and the Institute of Medicine (≥50/<50 nmol/l) thresholds. Linear mixed-effect regression models were employed to evaluate the association between vitamin D status and each outcome, considering interaction terms between vitamin D status and gestational age (P<0·1). At baseline, 70·7 % of pregnant women had 25(OH)D levels <75 nmol/l and 16 % had levels <50 nmol/l. Women with sufficient vitamin D status at baseline, using both thresholds, presented lower glycaemia than those with insufficient 25(OH)D. Pregnant women with 25(OH)D concentrations <75 nmol/l showed lower insulin (β=-0·12; 95 % CI -0·251, 0·009; P=0·069) and adiponectin (β=-0·070; 95 % CI -0·150, 0·010; P=0·085) concentrations throughout pregnancy than those with 25(OH)D levels ≥75 nmol/l. Pregnant women with 25(OH)D <50 nmol/l at baseline presented significantly higher leptin concentrations than those with 25(OH)D levels ≥50 nmol/l (β=-0·253; 95 % CI -0·044, 0·550; P=0·095). The baseline status of vitamin D influences the biomarkers involved in glucose metabolism. Vitamin D-sufficient women at baseline had higher increases in insulin and adiponectin changes throughout gestation than those who were insufficient.

The high maternal TG level at early trimester was associated with the increased risk of LGA newborn in non-obesity pregnant women

IntroductionRecent research had shown blood glucose was not the only cause of large for gestational age infant (LGA), the contributions of other fuels such as lipids also play an important role in fetal development. However the association between maternal triglyceride at early trimester and the risk of LGA has not yet been clearly elucidated. This research evaluated the association of maternal early trimester TG level with the risk of LGA infant in Chinese mothers.Methods2839 pregnant women were recruited at the first visit of their perinatal health care and followed up prospectively till after delivery. The demographic, maternal characteristics were extracted from a questionnaire. Infant characteristics were collected at delivery. Maternal fasting serum total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), and low density lipoprotein cholesterol (HDL-C)levels, were measured in 6~8th, 16th, 24th, and 36th gestational weeks. Fasting serum glucose levels were measured at 6~8th, 24th, and 36th gestational weeks. Logistic regression model was used to calculate the odds ratio (OR) and 95% confidence intervals.ResultsA consistently lower TG level was observed in mothers with non-LGA infant than mothers with LGA infant and TG level of mothers of LGA infants increased faster than that of control group. The incidence of LGA infants between two groups (TG<1.7 mmol/L and TG ≥ 1.7 mmol/L) was 14.46 and 26.63%, respectively. Mothers with the highest TG level (TG > 1.19 mmol/L) gave birth to infants with higher birth weight (BW) than the other two groups (TG < 0.70 mmol/L and TG:0.70~0.89 mmol/L). When stratified by pre-pregnancy body mass index (pre-BMI), a significantly positive association was founded between the maternal TG level at early trimester and the risk of LGA in non-overweight/obesity women (OR = 1.740, p = 0.034).ConclusionsThe findings suggested that high maternal TG level at very early trimester was associated with the increased risk of LGA in non-overweight/obesity pregnant women. Moreover, high maternal TG level at first trimester may be an early predictor of LGA.

Intimate partner violence during pregnancy in Vietnam: prevalence, risk factors and the role of social support

ABSTRACTBackground: Violence against women is a global public health problem. A better understanding of risk factors for intimate partner violence (IPV) exposure during pregnancy is important to develop interventions for supporting women being exposed to IPV.Objective: The purpose of this study was to measure the prevalence of IPV during pregnancy and analyse how social support and various risk factors are associated with IPV.Methods: A cross-sectional study conducted among 1309 pregnant women in Dong Anh district, Vietnam. Information about socio-economic conditions and previous exposure to IPV was collected when women attended antenatal care before the 24th gestational week. Information about social support information and exposure to IPV during pregnancy was collected in the 30th-34th gestational week. Multivariable regression was used to identify associations between IPV, social support and other potential risk factors.Results: The prevalence of IPV exposure during pregnancy was 35.2% (Emotional violence: 32.2%; physical violence: 3.5% and sexual violence: 9.9%). There was a statistically significant association between previous IPV exposure, lack of social support and IPV exposure during pregnancy. After adjustment for socioeconomic characteristics, pregnant women who had previously been exposed to IPV were more likely to be exposed IPV at least one time (AOR = 6.3; 95% CI: 4.9–8.2) as well as multiple times (AOR = 6.0; 95% CI: 4.5–8.0). Similarly, pregnant women having a lack of social support had a higher likelihood of being exposed to IPV at least one time (AOR = 3.1; 95% CI: 2.4–3.9) or multiple times (AOR = 2.9; 95% CI: 2.2–3.8).Conclusion: IPV is relatively high during pregnancy in Vietnam. Previous exposure to IPV and lack of social support is associated with increased risk of violence exposure among pregnant women in Vietnam.

Prediction of stillbirth in women with overweight or obesity-A register-based cohort study.

ObjectiveTo develop a model for prediction of stillbirth after the 28th gestational week in singleton pregnancies of women with overweight or obesity.MethodThis is a register-based cohort study. The first trimester screening database including data from 2006 until 2015 was cross-linked with the Swedish Medical Birth Register and the Swedish Register of Total Population. The final study cohort comprised 145,319 pregnancies, out of which 45,859 pregnancies were complicated by overweight or obesity and without pre-gestational diabetes. There were in total 282 stillbirths. Prediction models for stillbirth in pregnancies with overweight or obesity were constructed based on maternal characteristics, pregnancy complications and biochemical markers. Receiver Operating Characteristic (ROC) and area under curve (AUC) were calculated, based on logistic regression analyses.ResultsThe prevalence of stillbirth was 1.6/1000 births and 2.6/1000 births in normal weight and overweight/obese women, respectively. The final predictive model had an AUC of 0.69 (95% CI: 0.64–0.74) with a sensitivity of 28% at a 90% fixed specificity.ConclusionsIt is possible to predict 28% of stillbirths in overweight or obese women, at a false positive rate of 10%. In particular, growth-restricted fetuses are at increased risk of stillbirth.

A Case of Rudimentary Horn Pregnancy Diagnosed After Failed Attempts at Pregnancy Termination

: We present a case of rudimentary horn pregnancy in the 18th gestational week with fetal demise and treatment failure. After failure in pregnancy termination, the patient was admitted to a tertiary care hospital. Following laparatomy, a definitive diagnosis was confirmed. Laparotomy was performed to remove the rudimentary horn and ipsilateral fallopian tube. Overall, physicians should be cautious about the risk of uterine disorders in the event of several failures in terminating pregnancy.

Retrospective analysis of indications for termination of pregnancy

This is a retrospective study of 139 termination of pregnancies (TOPs) between November 2015 and November 2017 to demonstrate the indications. We have shown that 60.4%, 34.5% and 5% of the terminations were performed because of genetic disorders, foetal or obstetrical problems, and maternal causes, respectively. Congenital abnormalities (43.8%), anhydramniosis (17.2%) and chromosomal abnormalities (15.1%) were the most frequent causes of the TOPs. The central nervous system seemed to be the most frequent indicator found in our study. The critical finding is the presence of nine (6.4%) terminations because of foetal reasons beyond the 24th gestational week. A vaginal termination occurred in 91.4% of cases, whereas a hysterotomy was performed in 8.6% of the cases. Previous uterine surgery was the most significant risk factor for a hysterotomy. Knowing the foetal indications is essential to know the aetiological and medico-legal backgrounds of the TOPs for better planning and medical counselling. Impact statement What is already known on this subject? Congenital anomalies are most common cause of termination of wanted pregnancies. Terminations beyond 24 weeks are also evaluated as unethical and create an ethical concern. The legal limitations differ between countries in terms of the legal limit in pregnancy for terminations. What do the results of this study add? We have demonstrated the congenital anomalies are the most common reason for pregnancy terminations after excluding fetal demise and unwanted pregnancies. We also showed that congenital anomalies and chromosomal abnormalities are most common indications for terminations of pregnancies beyond 24 weeks. The legal arrangements related to the termination of pregnancies in Turkey are described. Prior uterine surgery is a significant risk factor for hysterotomies in the termination of pregnancies. What are the implications of these findings for clinical practice and/or further research? It is critical to know the aetiological background of termination of pregnancies for better planning and consultation.

Pregnancy and post-partum muscle and cerebral oxygenation during intermittent exercise in gestational diabetes: A pilot study

ObjectiveThis pilot, prospective, observational, cohort study aimed to examine, for the first time, the in vivo alterations in the oxygenation of the forearm skeletal muscles and the prefrontal lobes during intermittent exercise in women diagnosed with gestational diabetes mellitus (GDM), during and after pregnancy. Study DesignNine pregnant women, diagnosed with GDM, performed a 3-min intermittent handgrip exercise protocol (at 35% of Maximal Voluntary Contraction) during pregnancy (mean 27th gestational week) and following labor (mean 71 weeks). During the protocol, muscle and cerebral oxygenation were assessed with near-infrared spectroscopy. Resting vascular parameters [carotid intima-media thickness (cIMT) and hemodynamic parameters (using rheocardiography)], and hematological/biochemical parameters during pregnancy and after delivery have been compared. ResultsAlthough changes were observed in certain hematological parameters (p< 0.05), cIMT and hemodynamic parameters were not altered post-partum. In addition, both muscle and cerebral oxygenation parameters during handgrip were not significantly altered post-partum. ConclusionsDespite significant changes in specific hematological parameters in women with GDM, impairments in muscle and cerebral oxygenation during exercise remained at one year after labor. These results indicate that alterations in vascular parameters and muscle/cerebral oxygenation associated with GDM do not entirely reverse post-partum. Future studies are needed to examine which interventions will lead to improvements in microvascular parameters and prevent type 2 diabetes.

Insights from outside BJOG

Insights from outside BJOG

Development of Hard and Soft Palate During the Fetal Period and Hard Palate Asymmetry

In the present study, it was aimed to perform the morphometric analysis of the hard and soft palate in fetal cadavers and evaluate hard palate asymmetry during the fetal development. The development of the palate was investigated in 40 (21 males, 19 females) fetal materials aged between the 17th and 40th gestational week. In this study, distances between the incisive papilla-staurion (Ip-Sr), staurion-posterior nasal spine (Sr-Pns), incisive papilla-greater palatine foramen (Ip-Gpf) on the right and left sides, Sr-Gpf, and Pns-Gpf were measured. In cases with asymmetry, the ratio of asymmetry was determined in percentage using the asymmetry index. Moreover, angular values between Ip-Sr-Gpf and Ip-Pns-Gpf on the right and left sides were measured, and the right and left side values were compared with each other. The hard and soft palate lengths were measured on the planum medianum. Upon comparing the measured parameters between males and females, the mean values of male fetuses were higher in all parameters, but a significant difference was found only in the Sr-Pns distance among these parameters. Upon comparing the angular data and asymmetry index data on the hard palate between the trimester groups, a significant difference was found only in the Ip-Sr-Gpf (left) parameter. The mean ratio of the hard palate to the soft palate was found as 1.90. It is believed that the obtained data will contribute to studies to be conducted in fields such as plastic surgery, maxillofacial surgery, intrauterine surgery, fetopathology, embryology, anatomy, and obstetrics.

Histogenesis of uterus in human fetuses

IntroductionThe histological changes during the development of the human uterus throughout the fetal period exhibit varying cellular patterns in the lining epithelium. The present study documents these progressive changes during fetal uterine maturation. Methods70 fetal uteri whose age varies from 14th to 40th gestational weeks without any external anomalies were studied. ResultsAt 14 weeks, the uterine lining epithelium is predominantly pseudostratified columnar, the nuclei being arranged at varying levels. However, the lower part of cervix shows epithelium comprising of a mosaic of flat or slightly raised polygonal cells which gradually changes to stratified squamous epithelium with advancing gestation. From 32 weeks onwards, the pseudostratification of uterine epithelium changes to simple columnar epithelium progressively. At 14 weeks, two distinct layers of mesenchymal cells are apparent, elongated cells in abundance at the subserosal layer and sparsely arranged rounded cells towards the lumen. Endometrial glands appear by the 17th week. DiscussionExcept for the lower part of cervix, pseudostratified columnar epithelium lines the fetal uterus. As gestation progresses, pseudostratification gradually changes to simple columnar epithelium. The palmate folds of the epithelium appear by 17 weeks in cervical canal. The smooth muscle bundle appears by 24 weeks of gestation. Undifferentiated mesenchymal cells around paramesonephric duct develop into both smooth muscles and endometrial cells.

Mutation analysis and prenatal diagnosis for a pedigree affected with maple syrup urine disease

To carry out mutation analysis for a pedigree affected with maple syrup urine disease (MSUD). Clinical data of the proband was collected. Potential mutations of the BCKDHA and BCKDHB genes were analyzed by PCR and Sanger sequencing. Prenatal diagnosis was provided to a high-risk fetus at 12th gestational week through chorionic villus sampling. Two heterozygous mutations c.284G>C (p.Gly95Ala) and c.853C>T (p.Arg285*) of the BCKDHB gene were identified in the proband, which were inherited from his mother and father, respectively. Among these, c.853C>T (p.Arg285*) was known to be pathogenic, while c.284G>C (p.Gly95Ala) was a novel mutation. Prenatal diagnosis showed that the fetus has inherited the c.284G>C (p.Gly95Ala) mutation from its mother but no mutation from its father. After birth, the infant appeared to be healthy. The compound heterozygous mutations c.284G>C (p.Gly95Ala) and c.853C>T (p.Arg285*) probably underlie the pathogenesis of MUSD in the proband. Mutation analysis can facilitate prenatal diagnosis and genetic counseling for the affected families.

EP11.01: Prenatal ultrasound‐based diagnosis of fetal OEIS complex associated with lower limb polymelia and cardiac, hepatic dysplasia

Omphalocele exstrophy imperforate anus spinal defects (OEIS) complex is a type of congenital malformation syndrome involving multiple fetal systems. Its characteristic ultrasonographic features include omphalocele, spinal defects, absence of bladder, and ambiguous anus and genitalia, and it is often accompanied with limb malformations. Here, we report a case of fetal OEIS complex combined with lower limb polymelia and cardiac, hepatic dysplasia at the 24th gestational week diagnosed on prenatal ultrasonography. The ultrasonogram showed an omphalocele on the right side of the umbilical cord entry, spinal meningocele at the lumbosacral portion, bladder absence and ambiguous genitalia. Concurrent multiple malformations included lower extremity multi-limb deformity, feet abnormity, congenital ventricular septal defect, three-lobe liver malformation, ectopic kidneys, and single umbilical artery. Besides characteristic ultrasonographic features of OEIS complex, this case was combined with severe and rare lower limb polymelia and multi-lobe liver deformity. It was easily missed diagnosis when oligoamnios and the liver bulged. This case will strengthen our understanding of such rare deformities and provide reference information for early diagnosis of similar cases. Supporting information can be found in the online version of this abstract Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Fetal heart rate monitoring device using condenser microphone sensor: Validation and comparison to standard devices

Fetal heart rate (FHR) monitoring device is highly demanded to assess the fetus health condition in home environments. Conventional standard devices such as ultrasonography and cardiotocography are expensive, bulky and uncomfortable and consequently not suitable for long-term monitoring. Herein, we report a device that can be used to measure fetal heart rate in clinical and home environments. The proposed device measures and displays the FHR on a screen liquid crystal display (LCD). The device consists of hardware that comprises condenser microphone sensor, signal conditioning, microcontroller and LCD, and software that involves the algorithm used for processing the conditioned fetal heart signal prior to FHR display. The device's performance is validated based on analysis of variance (ANOVA) test. FHR data was recorded from 22pregnant women during the 17th to 37th week of gestation using the developed device and two standard devices; AngelSounds and Electronic Stethoscope. The results show that F-value (1.5) is less than F𝑐𝑟𝑖𝑡, (3.1) and p-value (p> 0.05). Accordingly, there is no significant difference between the mean readings of the developed and existing devices. Hence, the developed device can be used for monitoring FHR in clinical and home environments.

Associations of maternal oestradiol, cortisol, and TGF-β1 plasma concentrations with thyroid autoantibodies during pregnancy and postpartum.

Thyroid physiology and autoimmunity are altered in pregnancy. While oestradiol, cortisol, and TGF-β1 are implicated in these phenomena outside pregnancy, their associations with thyroid autoantibodies during pregnancy and postpartum are not thoroughly examined. This study aimed to unravel their eventual associations during pregnancy and postpartum in the same cohort of 93 pregnant women studied prospectively from 2015 to 2017. Blood samples were drawn at the 24th and the 36th gestational week and at the 1st postpartum week for measurements of thyroid hormones, TSH, anti-TPO, anti-Tg, oestradiol, cortisol, and TGF-β1. Serum anti-TPO was greater (P<0.05) at the 1st postpartum than at the 24th and 36th gestational weeks. At the 36th gestational week, cortisol was greater (P<0.05) and TGF-β1 lower (P<0.05) than at the 24th gestational and the 1st postpartum weeks. At the 1st postpartum week, cortisol correlated negatively with anti-Tg (r=-0.419) (P<0.05). ΔTGF-β1 was the best negative and Δoestradiol the best positive predictor of the 1st postpartum week anti-TPO (P<0.05, b=-0.509; P<0.05, b=0.459 respectively). At postpartum, increased TGF-β1 is related to a less pronounced anti-TPO increase as compared to the 3rd trimester, suggesting an immunosuppressive role for TGF-β1. During pregnancy and postpartum, oestradiol, cortisol, and TGF-β1 are associated with suppression of thyroid autoantibodies.

Traffic-Related Air Pollution and Pregnancy Loss

Background. Traffic-related air pollution has been linked to multiple adverse pregnancy outcomes. However, few studies have examined pregnancy loss, targeting losses identified by hospital records, a large limitation as it does not capture events not reported to the medical system.Methods. We used a novel variation of the time-series design to determine the association, and identify the critical window of vulnerability, between week-to-week traffic-related air pollution and conceptions resulting in live births, using nitrogen dioxide (NO2) as a traffic emissions tracer. We used information from all live births recorded at Beth Israel Deaconess Medical Center (BIDMC) in Boston, MA (2000&amp;#8211;2013) and all live births in Tel Aviv District, Israel (2010&amp;#8211;2013). For exposure assessment, in Boston we used the average of 5 urban monitoring sites, while in Tel Aviv the district average of a spatio-temporal prediction model.Results: In Tel Aviv District, the strongest estimate was during the 16th gestational week; for every 10 ppb of NO2 we observed a decreased rate of live births (RR&amp;#61;0.82; 95%CI: 0.76&amp;#8211;0.90), using live-birth identified conceptions to infer pregnancy losses. In Boston, the strongest estimate was during the 15th gestational week; we observed a RR &amp;#61; 0.87 (95%CI: 0.78&amp;#8211;0.97), among women living within 60 km from BIDMC, and RR &amp;#61; 0.84 (95%CI: 0.74&amp;#8211;0.96) in week 17 among those within 20 km from BIDMC.Conclusions: Using weekly conceptions ending in a live birth rather than identified pregnancy losses, we for the first time comprehensively considered the relationship between air pollution and all pregnancy loss throughout gestation. The observed results, with remarkable similarity in two independent locations, suggest that at levels of traffic pollution experienced in Boston and Israel, higher levels are associated with pregnancy loss with strongest estimates between the 10th&amp;#8211;20th gestational weeks.

Identifying windows of susceptibility for maternal exposure to ambient air pollution and preterm birth

Maternal exposure to ambient air pollution has been associated with preterm birth (PTB), however, entire pregnancy or trimester-specific associations were generally reported, which may not sufficiently identify windows of susceptibility. Using birth registry data from Guangzhou, a megacity of southern China (population ~14.5 million), including 469,975 singleton live births between January 2015 and July 2017, we assessed the association between weekly air pollution exposure and PTB in a retrospective cohort study. Daily average concentrations of PM2.5, PM10, NO2, SO2, and O3 from 11 monitoring stations were used to estimate district-specific exposures for each participant based on their district residency during pregnancy. Distributed lag models (DLMs) incorporating Cox proportional hazard models were applied to estimate the association between weekly maternal exposure to air pollutant and PTB risk (as a time-to-event outcome), after controlling for temperature, seasonality, and individual-level covariates. We also considered moderate PTB (32–36 gestational weeks) and very PTB (28–31 gestational weeks) as outcomes of interest. Hazard ratios (HRs) and 95% confidential intervals (95% CIs) were calculated for an interquartile range (IQR) increase in air pollutants during the study period. An IQR increase in PM2.5 exposure during the 20th to 28th gestational weeks (27.0 μg/m3) was significantly associated with PTB risk, with the strongest effect in the 25th week (HR = 1.034, 95% CI:1.010–1.059). The significant exposure windows were the 19th–28th weeks for PM10, the 18th–31st weeks for NO2, and the 23rd–31st weeks for O3, respectively. The strongest associations were observed in the 25th week for PM10 (IQR = 37.0 μg/m3; HR = 1.048, 95% CI:1.034–1.062), the 26th week for NO2 (IQR = 29.0 μg/m3; HR = 1.060, 95% CI:1.028–1.094), and in the 28th week for O3 (IQR = 90.0 μg/m3; HR = 1.063, 95% CI:1.046–1.081). Similar patterns were observed for moderate PTB (32–36 gestational weeks) and very PTB (28–31 gestational weeks) for PM2.5, PM10, NO2 exposure, but the effects were greater for very PTB. We did not observe any association between pregnancy SO2 exposure and the risk of PTB. Our results suggest that middle to late pregnancy is the most susceptible air pollution exposure window for air pollution and PTB among women in Guangzhou, China.