Mitigating Health-Related Uncertainties During Pregnancy: The Role of Smart Health Monitoring Technologies.

Pregnancy is a time filled with uncertainties, which can be challenging and lead to fear or anxiety for expectant parents. Health monitoring technologies that allow monitoring of the vital signs of both the mother and fetus offer a way to address health-related uncertainties. But are smart health monitoring technologies (SHMTs) actually an effective means to reduce uncertainties during pregnancy, or do they have the opposite effect? Using conceptual reasoning and phenomenological approaches grounded in existing literature, this Viewpoint explores the effects of SHMTs on health-related uncertainties during pregnancy. The argument posits that while SHMTs can alleviate some health-related uncertainties, they may also create new ones. This is particularly the case when the abundance of vital data overwhelms pregnant persons, leads to false-positive diagnoses, or raises concerns about the accuracy and analysis of data. Consequently, it is concluded that the use of SHMTs is not a cure-all for overcoming health-related uncertainties during pregnancy. Since the use of such monitoring technologies can introduce new uncertainties, it is important to carefully consider where and for what purpose they are used, use them sparingly, and promote a pragmatic approach to uncertainties.Using conceptual reasoning and phenomenological approaches grounded in existing literature, the effects of SHMTs on health-related uncertainties during pregnancy are explored. The argument posits that while SHMTs can alleviate some health-related uncertainties, they may also create new ones. This is particularly the case when the abundance of vital data overwhelms pregnant persons, leads to false-positive diagnoses, or raises concerns about the accuracy and analysis of data. Consequently, it is concluded that the use of SHMTs is not a cure-all for overcoming health-related uncertainties during pregnancy. Since the use of such monitoring technologies can introduce new uncertainties, it is important to carefully consider where and for what purpose they are used, use them sparingly, and promote a pragmatic approach to uncertainties.

Pregnancy in Times of War: What Are the Fallouts? A Review.

BACKGROUND: The beginning of the conflict in Ukraine has reminded Europeans of the many and diverse consequences of armed conflicts. Indeed, the ever more sophisticated conflicts have led to the diffusion of numerous chemicals whose consequences spread even after the end of the war. We present through this paper a review of the consequences of pregnancies from the major conflicts that took place since the end of World War II. SUMMARY: MEDLINE, Web of Science, and Embase were screened for articles linking perinatal death (PD) or birth defects (BD) to wartime. A total of 50 papers treating 8 countries and 4 major and medically documented conflicts were included in the final analysis. An increase in BD and PD during and after the end of the conflicts was reported through all the conflicts analyzed. KEY MESSAGE: While more data are needed to conclude, maternal-fetal medicine specialists ought to be wary when dealing with exposed populations.

Connecting clinical, environmental, and genetic factors point to an essential role for vitamin A signaling in the pathogenesis of congenital diaphragmatic hernia.

Congenital diaphragmatic hernia (CDH) is a developmental disorder that results in incomplete diaphragm formation, pulmonary hypoplasia, and pulmonary hypertension. Although a variety of genes have been linked to its etiology, CDH is not a monogenetic disease, and the cause of the condition is still unclear in the vast majority of clinical cases. By comparing human clinical data and experimental rodent data from the literature, we present clear support demonstrating the importance of vitamin A (vitA) during the early window of pregnancy when the diaphragm and lung are forming. Alteration of vitA signaling via dietary and genetic perturbations can create diaphragmatic defects. Unfortunately, vitA deficiency is chronic among people of child-bearing age, and this early window of diaphragm development occurs before many might be aware of pregnancy. Furthermore, there is an increased demand for vitA during this critical period, which exacerbates the likelihood of deficiency. It would be beneficial for the field to further investigate the connections between maternal vitA and CDH incidence, with the goal of determining vitA status as a CDH risk factor. Regular clinical monitoring of vitA levels in child-bearing years is a tractable method by which CDH outcomes could be prevented or improved.

Effects of bipolar disorder on maternal and fetal health during pregnancy: a systematic review.

BACKGROUND: Bipolar disorder (BD) is a mental disorder characterized by mood shifts from severe depression to mania. Pregnant women with BD may experience manic or depressive episodes, so they are usually concerned about the effects of BD on their pregnancy. The aim of this systematic review is to determine the effects of BD on maternal health and fetal health, weight, and development. It also addresses how BD affects the probability of incidence of pregnancy complications in women with bipolar compared with healthy controls. METHODS: Seven electronic databases (Ovid MEDLINE, Embase, MIDRIS, APA PsychINFO, Scopus, Web of Science, and ScienceOpen) were searched, and 1728 eligible studies were identified. After deduplication, screening, and manual search processes, we included only 15 studies. Descriptive analysis, and calculation of the probability of incidence for each pregnancy outcome were used to analyze the results. RESULTS: The findings of the included studies suggest that BD during pregnancy may affect both fetal growth and maternal health by increasing the risk of giving birth to an infant with some birth defects such as microcephaly, CNS problems, small for gestational age, and other congenital anomalies, in addition to causing some obstetric complications such as gestational hypertension, preterm labor, need for assisted delivery, hospital readmission, and others. CONCLUSION: Bipolar disorder during pregnancy negatively affects mothers and their fetuses and increases the probability of incidence of obstetrics complications.

Impact of prenatal exposure to metallic elements on neural tube defects: Insights from human investigations.

Metallic elements play a pivotal role in maternal and fetal health. Metals can cross the placental barrier and be absorbed by fetuses, where they may affect closure of the neural tube during embryonic development. Neural tube defects (NTDs), which result from aberrant closure of the neural tube three to four weeks post-conception, have a multifactorial and complex etiology that combines genetic variants and environmental exposure. Recent advances in population-level association studies have investigated the link between maternal environmental exposure and NTDs, particularly the influence of metals on the incidence of NTDs. Herein, we present a broad and qualitative review of current literature on the association between maternal and prenatal metal exposure via the maternal peripheral blood, amniotic fluid, placenta, umbilical cord, and maternal hair, and the risk of developing NTDs. Specifically, we identify the various aggravating or attenuating effects of metallic exposure on the risk of NTD formation. This review provides novel insights into the association between environmental metals and NTDs and has important applications for NTD prevention and mitigating environmental exposure to metals.

Wearable technology for health monitoring during pregnancy: an observational cross-sectional survey study.

PURPOSE: To evaluate how women of child-bearing age perceive the use of remote fetal ECG monitoring technologies. Telemedicine has advanced to the forefront of healthcare delivery, including maternal-fetal medicine. Smart wearable electrocardiogram (ECG) devices can enable pregnant women to monitor their health and that of their fetuses. Such technology would be a logical extension of the telemedicine ecosystem. METHODS: We conducted an observational cross-sectional study via online surveying in the United States. Study participants were recruited using the SurveyMonkey Audience Polling system and responded virtually. In all, the sample consisted of 507 women, aged 18-45 from 45 states, who are expecting to become pregnant in the next five years. Women were asked to identify their willingness to use a wearable ECG device the size of a patch-sized large band-aid on their abdomen. Ten binary or multiple-choice questions were used to gauge population interest and related demographics toward the usage of a wearable ECG device. RESULTS: Of the 507 participants, 461 (91%) women expressed an acceptance of wearable ECG technology throughout the pregnancy as a mechanism for increased frequency of monitoring of maternal and fetal health outside the hospital. 395 (78%) women demonstrated a willingness to wear devices day and night or at least during sleep and 213 (42%) of the women would spend up to $200 on such a device. CONCLUSION: Even though conducted prior to the COVID-19 pandemic, this study clearly indicates a high degree of readiness of prospective pregnant women for telemedicine with continuous health monitoring of the mother-fetus dyad.

From Biomarkers to the Molecular Mechanism of Preeclampsia-A Comprehensive Literature Review.

Preeclampsia (PE) is a prevalent obstetric illness affecting pregnant women worldwide. This comprehensive literature review aims to examine the role of biomarkers and understand the molecular mechanisms underlying PE. The review encompasses studies on biomarkers for predicting, diagnosing, and monitoring PE, focusing on their molecular mechanisms in maternal blood or urine samples. Past research has advanced our understanding of PE pathogenesis, but the etiology remains unclear. Biomarkers such as PlGF, sFlt-1, PP-13, and PAPP-A have shown promise in risk classification and preventive measures, although challenges exist, including low detection rates and discrepancies in predicting different PE subtypes. Future perspectives highlight the importance of larger prospective studies to explore predictive biomarkers and their molecular mechanisms, improving screening efficacy and distinguishing between early-onset and late-onset PE. Biomarker assessments offer reliable and cost-effective screening methods for early detection, prognosis, and monitoring of PE. Early identification of high-risk women enables timely intervention, preventing adverse outcomes. Further research is needed to validate and optimize biomarker models for accurate prediction and diagnosis, ultimately improving maternal and fetal health outcomes.

Scientific, ethical, and legal considerations for the inclusion of pregnant people in clinical trials.

Clinical trials to address the COVID-19 public health emergency have broadly excluded pregnant people from participation, illustrating a long-standing trend of clinical trial exclusion that has led to a clear knowledge gap and unmet need in the treatment and prevention of medical conditions experienced during pregnancy and of pregnancy-related conditions. Drugs (includes products such as drugs, biologics, biosimilars and vaccines) approved for a certain medical condition in adults are also approved for use in pregnant adults with the same medical condition, unless contraindicated for use in pregnancy. However, there are limited pregnancy-specific data on risks and benefits of drugs in pregnant people, despite their approval for all adults. The United States Food and Drug Administration-approved medical products are used widely by pregnant people, 90% of whom take at least 1 medication during the course of their pregnancy despite there being sparse data from clinical trials on these products in pregnancy. This overall lack of clinical data precludes informed decision-making, causing clinicians and pregnant patients to have to decide whether to pursue treatment without an adequate understanding of potential effects. Although some United States Food and Drug Administration initiatives and other federal efforts have helped to promote the inclusion of pregnant people in clinical research, broader collaboration and reforms are needed to address challenges related to the design and conduct of trials that enroll pregnant people, and to forge a culture of widespread inclusion of pregnant people in clinical research. This article summarizes the scientific, ethical, and legal considerations governing research conducted during pregnancy, as discussed during a recent subject matter expert convening held by the Duke-Margolis Center for Health Policy and the United States Food and Drug Administration on this topic. This article also recommends strategies for overcoming impediments to inclusion and trial conduct.

Giving sleep position advice in pregnancy: Will we make women anxious?

BACKGROUND: There is now robust evidence that when women settle to sleep on their back in late pregnancy (>28 weeks) they are at increased risk of stillbirth. Therefore, there are several stillbirth prevention programs worldwide that have begun advising pregnant women to adopt a side position when settling to sleep in late pregnancy. However, some hold concerns that giving women information about sleep position and stillbirth risk may make them anxious. AIM: This study aimed to determine what influences how 'safe sleep' messages are perceived by pregnant women and if there is anxiety associated with receiving this message. MATERIALS AND METHODS: An online survey of 537 Australian women (n = 97 were 'currently pregnant'). The survey examined participant's views regarding sleep position messages, type of information source as well as participant characteristics such as general anxiety and their fetal health locus of control (FHLC). RESULTS: Our findings suggest that the FHLC may influence how health messaging regarding sleep in pregnancy is perceived and acted upon. We have also shown a subset of pregnant women may feel anxiety associated with the sleep position in pregnancy message. This may not be related to history of anxiety, but rather to their higher 'internal' FHLC, ie those who reflect a greater sense of personal agency over fetal health. CONCLUSIONS: Our findings suggest most women will perceive information about settling into sleep position as informative rather than anxiety provoking. Therefore, maternity care providers should not be overly concerned about provoking anxiety when providing this information.

Satisfaction with and Feasibility of Prenatal Counseling via Telemedicine: A Prospective Cohort Study.

Introduction: Telemedicine has become increasingly important over the past decade. With the pressure of the COVID-19 pandemic, demands for remote health care solutions have seen an unprecedented rise. However, many questions regarding the feasibility and benefits of telemedicine remain. The aim of our study was to evaluate both the technical feasibility and patient satisfaction with video consultations in a tertiary center for obstetric care. Materials and Methods: This prospective single-center trial was part of the larger open Video Service project on telemedicine at the Department of Gynecology and Obstetrics at the University of Münster. Patients requiring prenatal or prepregnancy counseling were included. A questionnaire was designed for the evaluation of patient satisfaction and filled in by both patient and health care provider at the end of the video consultation. Results: Of 80 eligible cases, 75 video consultations were carried out and data from the questionnaire were collected. Overall patient satisfaction was high (95%, 71/75) although technical problems occurred in 37% (29/75) of the appointments. Health care providers' satisfaction was equally high and in 88% (66/75) of cases, remote consultations avoided an in-house visit without effect on health care quality. Conclusions: Remote consultations are feasible and yield high satisfaction rates even in a medical field as sensitive as perinatal medicine. Further research is necessary to determine the cost-effectiveness and effects on perinatal outcome. Health care systems should be offered clear guidance on medicolegal issues and funding of remote consultations to integrate telemedicine into routine health care.

Clinical Implication of Immunohaematological Tests in ABO haemolytic disease of newborn: Revisiting an old disease.

OBJECTIVE: We aimed to assess the frequency distribution of of ABO haemolytic disease of newborn (ABO-HDN) and to know the predictive value of immunohaematological tests in identifying at risk neonates. BACKGROUND: ABO incompatibility, although a common cause of haemolytic disease of newborn, has several unaddressed issues related to it. MATERIAL AND METHODS: A prospective study over 20 months was carried out in a tertiary care centre in South India. Blood grouping, Direct Antiglobulin test (DAT) and elution studies were performed on neonatal samples, whereas blood grouping, antibody screening and antibody titration were performed on maternal samples. In suspected cases, ABO-HDN was diagnosed after excluding other possible causes for haemolysis. The laboratory results were correlated with the clinical details to assess the predictive value of the tests. RESULTS: Of the total 2856 pregnancies, 34% had ABO incompatibility. On testing with columnagglutination test (CAT), the overall DAT positivity and that among ABO-incompatible cases were 3.8% and 11.2%, respectively,) whereas by conventinal tube technique (CTT) it was 0.6% and 2.4% respectively. CAT was found to have higher sensitivity, and the predictive value was higher for CTT. Maternal IgG titre showed a positive linear relationship with the DAT strength and the rise in indirect bilirubin levels. The positive predictive value of combination of tests such as DAT, elution and titation was 94.12%, which was much higher than that of the individual tests. CONCLUSION: DAT positivity is a predictor of early rise in serum bilirubin level, and a combination of tests has a better predictive value than individual tests towards development of clinically significant hyperbilirubinemia in ABO-HDN.

Gold nanoparticle biodistribution in pregnant mice following intravenous administration varies with gestational age.

The use of nanoparticles (NPs) to deliver therapeutics to reproductive organs is an emerging approach to safely and effectively treat mothers and babies facing pregnancy complications. This study investigates the biodistribution of two different sized gold-based NPs in pregnant mice following systemic delivery as a function of gestational age. Poly(ethylene glycol)-coated 15 nm gold nanoparticles or 150 nm diameter silica core/gold nanoshells were intravenously administered to pregnant mice at gestational days (E)9.5 or 14.5. NP distribution was analyzed twenty-four hours later by inductively coupled plasma-mass spectrometry and silver staining of histological specimens. More NPs accumulated in placentas than embryos and delivery to these tissues was greater at E9.5 than E14.5. Neither NP type affected fetal weight or placental weight, indicating minimal short-term toxicity in early to mid-stage pregnancy. These findings warrant continued development of NPs as tools to deliver therapeutics to reproductive tissues safely.

Overexpression of microRNAs miR-25-3p, miR-185-5p and miR-132-3p in Late Onset Fetal Growth Restriction, Validation of Results and Study of the Biochemical Pathways Involved.

In a prospective study, 48 fetuses were evaluated with Doppler ultrasound after 34 weeks and classified, according to the cerebroplacental ratio (CPR) and estimated fetal weight (EFW), into fetuses with normal growth and fetuses with late-onset fetal growth restriction (LO-FGR). Overexpression of miRNAs from neonatal cord blood belonging to LO-FGR fetuses, was validated by real-time PCR. In addition, functional characterization of overexpressed miRNAs was performed by analyzing overrepresented pathways, gene ontologies, and prioritization of synergistically working miRNAs. Three miRNAs: miR-25-3p, miR-185-5p and miR-132-3p, were significantly overexpressed in cord blood of LO-FGR fetuses. Pathway and gene ontology analysis revealed over-representation of certain molecular pathways associated with cardiac development and neuron death. In addition, prioritization of synergistically working miRNAs highlighted the importance of miR-185-5p and miR-25-3p in cholesterol efflux and starvation responses associated with LO-FGR phenotypes. Evaluation of miR-25-3p; miR-132-3p and miR-185-5p might serve as molecular biomarkers for the diagnosis and management of LO-FGR; improving the understanding of its influence on adult disease.

The Intergenerational Impact of Terror: Did the 9/11 Tragedy Impact the Initial Human Capital of the Next Generation?

Given the unexpected nature of the terrorist attacks of September 11, 2001, a specific cohort of children were exogenously exposed to increased maternal psychological stress in utero. Rich administrative data and the precise timing of the event allow this study to uniquely provide insights into the health effects of exposure to maternal psychological stress across gestation. Results suggest that children exposed in utero were born significantly smaller and earlier than previous cohorts. The timing of the effect provides evidence that intrauterine growth is specifically restricted by first trimester exposure to stress; reductions in gestational age and increases in the likelihood of being born at low (<2,500 grams) or very low (<1,500 grams) birth weight are induced by increased maternal psychological stress mid-pregnancy. This study also documents a positively selected post-attack fertility response, which would bias an evaluation that includes cohorts conceived after September 11, 2001, in the control group.

Trouble With the Curve: Pearls and Pitfalls in the Evaluation of Fetal Growth.

OBJECTIVES: Poor fetal growth is one of the most important findings on an obstetric ultrasound (US) examination. First-trimester US is the most accurate means for dating pregnancies; however, dating based on last menstrual period remains the standard for determining gestational age. Discrepancies between menstrual and US dating can lead to the overdiagnosis of in utero growth restriction (IUGR). This article will demonstrate that as long as the fetal growth falls along a curve that parallels normal growth curves, appropriate growth has occurred regardless of the gestational age and weight percentile that has been assigned to the fetus. METHODS: Following Institutional Review Board approval (HSD-00002969), 860 third-trimester fetal US examinations were retrospectively evaluated from January 1 through July 1, 2017, to determine whether they had normal growth curves. Outcome data on all cases were obtained from review of the medical records. RESULTS: Of 216 fetuses (25%) suspected of IUGR based on a weight below the 10th percentile, 6 developed true IUGR: 5 that led to emergent delivery of fetuses weighing less than a 1000 g and 1 in utero fetal demise. The remaining 210 fetuses all had normal outcomes. CONCLUSIONS: As long as the fetal growth falls along a curve that parallels normal growth curves, appropriate growth has occurred regardless of the gestational age and weight percentile that has been assigned to the fetus.

Is supine exercise associated with adverse maternal and fetal outcomes? A systematic review.

OBJECTIVE: Theoretical concerns regarding the supine position at rest due to the gravid uterus obstructing aorta and vena caval flow may impinge uterine blood flow (UBF) to the fetus and maternal venous return. DESIGN: Systematic review. DATA SOURCES: Online databases up to 11 December 2017. STUDY CRITERIA: Eligible population (pregnant without contraindication to exercise), intervention (frequency, intensity, duration, volume or type of supine exercise), comparator (no exercise or exercise in left lateral rest position, upright posture or other supine exercise), outcomes (potentially adverse effects on maternal blood pressure, cardiac output, heart rate, oxygen saturation, fetal movements, UBF, fetal heart rate (FHR) patterns; adverse events such as bradycardia, low birth weight, intrauterine growth restriction, perinatal mortality and other adverse events as documented by study authors), and study design (except case studies and reviews) published in English, Spanish, French or Portuguese. RESULTS: Seven studies (n=1759) were included. 'Very low' to 'low' quality evidence from three randomised controlled trials indicated no association between supervised exercise interventions that included supine exercise and low birth weight compared with no exercise. There was 'very low' to 'low' quality evidence from four observational studies that showed no adverse events in the mother; however, there were abnormal FHR patterns (as defined by study authors) in 20 of 65 (31%) fetuses during an acute bout of supine exercise. UBF decreased (13%) when women moved from left lateral rest to acute dynamic supine exercise. CONCLUSION: There was insufficient evidence to ascertain whether maternal exercise in the supine position is safe or should be avoided during pregnancy.

Inositol for the prevention of gestational diabetes: a systematic review and meta-analysis of randomized controlled trials.

PURPOSE: Inositol (ISL) embraces a family of simple carbohydrates with insulin-sensitizing properties, whose most common isoforms are Myo-inositol (MYO) and D-chiro inositol (DCI). The aim of the present study was to assess the efficacy and safety of ISL supplementation during pregnancy for the prevention of gestational diabetes (GDM). METHODS: We conducted a systematic literature search in electronic databases until October 2017. We included all randomized controlled trials (RCTs) comparing pregnant women with GDM who were randomized to either ISL (i.e., intervention group) or either placebo or no treatment (i.e., control group). The primary outcome was the preventive effect on GDM, defined as the rate of GDM in women without a prior diagnosis of GDM. Pooled results were expressed as odds ratio (OR) with a 95% confidence interval (95% CI). RESULTS: Five RCTs were included (including 965 participants). ISL supplementation was associated with lower rate of GDM (OR 0.49, 95% CI 0.24-1.03, p = 0.01) and lower preterm delivery rate (OR 0.35, 95% CI 0.17-0.74, p = 0.006). No adverse effects were reported. Adjusting for the type of intervention (MYO 2 g twice daily vs MYO 1100 mg plus DCI 27.6 mg daily), a significant effect was found only in patients receiving 2 g MYO twice daily. CONCLUSIONS: ISLs administration during pregnancy appears to be safe and may represent a novel strategy for GDM prevention. In particular, the double administration of MYO 2 g per day may improve the glycemic homeostasis and may reduce GDM rate and preterm delivery rate.

The Effect of Religious Belief on the Attitudes of Pregnant's Toward the Fetal Health.

The purpose of this study is to identify the effect of religious beliefs on the attitudes of pregnant women toward the health of the fetus. Pregnancy, one of the important periods of life, is a special period in terms of affecting both the mother's and the baby's health. Health beliefs and attitudes are the factors that have effects on mother-baby death rates (mortality)-which is one of the most important criteria showing health level of societies. However, the literature has limited number of studies on this issue. Volunteer participants who applied to the Gynecology and Obstetrics Polyclinic were administered a questionnaire in order to identify the frequency of performing worship practices. Women's beliefs about their roles in determining their fetus's health were measured using Fetal Health Locus of Control (FHLC) scale. FHCL scale is composed of 3 sub-scales which include Internality Locus of Control (FHLC-I), Chance Locus of Control (FHLC-C), and Powerful Others Locus of Control (FHLC-P). Non-normally distributed scale scores were analyzed with Mann-Whitney U test for two independent groups and Kruskal-Wallis test for three independent groups. The scores obtained from all the sub-scales of the FHLC scale according to the praying groups were statistically significant (p = 0.008, p < 0.001, p < 0.001, respectively). The sub-scale scores were not statistically significant according to the tendency of giving alms (p = 0.269, p = 0.695, p = 0.079, respectively). The FHLC-I and FHLC-P scores did not indicate differences according to the tendency of going to pilgrimage (p = 0.914, p = 0.578), but FHLC-C scores were significantly higher in those who tended to go to pilgrimage (p = 0.004). There was a significant relationship between the tendency of performing prayer and going to pilgrimage and attitudes toward performing double-triple tests and oral glucose tolerance test (p = 0.002, p = 0.035, respectively). Religious beliefs were influential on the attitudes of pregnant women toward the health of the fetal. Gynecologists should consider patients' religious belief sensitivity while recommending them screening tests or planning their medication.

Physical activity during pregnancy - past and present.

The possible implications of physical activity during the period of pregnancy have been much debated over recent decades. This brief appraisal integrates knowledge from an array of position papers, systematic reviews, meta-analyses, and recommendations provided by specialty board committees. The medical community is becoming more and more aware of the beneficial effects of mild and moderate physical activity on the mother and the fetus, including improved clinical correlates of subsequent vaginal delivery, as contrasted to the clearly unbeneficial effects of a sedentary lifestyle.

Climate change and fetal health: The impacts of exposure to extreme temperatures in New York City.

BACKGROUND: Climate change is projected to increase the frequency, intensity, and duration of heat waves while reducing cold extremes, yet few studies have examined the relationship between temperature and fetal health. OBJECTIVES: We estimate the impacts of extreme temperatures on birth weight and gestational age in Manhattan, a borough in New York City, and explore differences by socioeconomic status (SES). METHODS: We combine average daily temperature from 1985 to 2010 with birth certificate data in Manhattan for the same time period. We then generate 33 downscaled climate model time series to project impacts on fetal health. RESULTS: We find exposure to an extra day where average temperature <25 °F and >85 °F during pregnancy is associated with a 1.8 and 1.7 g (respectively) reduction in birth weight, but the impact varies by SES, particularly for extreme heat, where teen mothers seem most vulnerable. We find no meaningful, significant effect on gestational age. Using projections of temperature from these climate models, we project average net reductions in birth weight in the 2070-2099 period of 4.6g in the business-as-usual scenario. CONCLUSIONS: Results suggest that increasing heat events from climate change could adversely impact birth weight and vary by SES.