Probability Of Low Birth Weight Research Articles

The giving tree: impacts of deforestation on birth outcomes in Mexico

ABSTRACT Deforestation adversely impacts human health through mechanisms such as increased air pollution, shifts in disease vector distributions, and changes in local climate. Although the influence of deforestation on human health is recognized, its effects on infant health outcomes have been insufficiently studied. This paper examines the effects of deforestation on infant health by analysing birth certificate data from 2011 to 2021 across Mexican municipalities, combined with satellite-derived annual deforestation rates. We show that increased deforestation leads to decreased birth weight, higher rates of low birth weight (LBW), and reduced Apgar scores. Specifically, an increase of one standard deviation in deforestation results in a reduction of average birth weight by 19 grams, an increase in the probability of LBW by 0.43% points, and an increase in the probability of a low Apgar score by 4.7% points. These effects are consistently observed even after controlling for different definitions of forest cover, excluding data during the COVID-19 pandemic, and limiting the analysis to municipalities with at least 2% forest coverage. This study provides critical evidence that deforestation directly impairs newborn health in Mexico, highlighting a significant and underappreciated environmental cost with long-term implications for human capital.

The effects of gender-specific local labor demand on birth and later outcomes

We study the effects of local labor market conditions during early pregnancy on birth and later outcomes. Using a longitudinal survey of newborns in Japan, we find that improvements in employment opportunities increase the probability of low birth weight and premature birth. We also examine the effects of gender-specific labor market conditions. An increase in labor demand for women has a large negative effect on gestational age, especially for mothers who gave birth at relatively young ages. However, we find little evidence of a lasting negative effect of an increase in labor demand during early pregnancy on serious health conditions or developmental delays in early childhood. Using prefecture-level panel data, we confirm that the negative effect on infant birth weight is not driven by selective fertility and mortality.

Health of neonates born in the maternity hospital in Bern, Switzerland, 1880-1900 and 1914-1922.

The identification of factors impeding normal fetal development and growth is crucial for improving neonatal health. Historical studies are relevant because they show which parameters have influenced neonatal health in the past in order to better understand the present. We studied temporal changes of neonatal health outcomes (birth weight, gestational age, stillbirth rate) and the influence of different cofactors in two time periods. Moreover, we investigated particularly neonatal health in the wake of the 1918/19 influenza pandemic. Data were transcribed from the Bern Maternity Hospital and consists of two time periods: A) The years 1880, 1885, 1890, 1895 and 1900 (N = 1530, births' coverage 20%); B) The years 1914-1922 (N = 6924, births' coverage 40-50%). Linear regression models were used to estimate the effect of birth year on birth weight, and logistic regression models to estimate the effect of birth year and of the exposure to the pandemic on premature birth, stillborn and low birth weight (LBW). Mean birth weight increased only minimally between the two datasets; whereas, in the years 1914-1922, the preterm birth and stillbirth rates were markedly reduced compared with the years 1880-1900. Sex, parity, gestational age and maternal age were significantly associated with birth weight in both time periods. The probability of LBW was significantly increased in 1918 (OR 1.49 (95% CI 1.00-2.23)) and in 1919 (OR 1.55 (95% CI 1.02-2.36)) compared to 1914. Mothers who were heavily exposed to the influenza pandemic during pregnancy had a higher risk of stillbirth (OR 2.27 (95% CI 1.32-3.9)). This study demonstrated that factors influencing neonatal health are multifactorial but similar in both time periods. Moreover, the exposure to the 1918/19 pandemic was less associated with LBW and more associated with an increased risk of stillbirth. If this trend is confirmed by further studies, it could indicate some consistency across pandemics, as similar patterns have recently been shown for COVID-19.

The association of lowered alcohol prices with birth outcomes and abortions: A population-based natural experiment.

Alcohol use during pregnancy remains an important risk factor for adverse birth outcomes, but little is known regarding how alcohol prices affect pregnancy outcomes on the population level. We assess the associations between decreased alcohol prices with birth outcomes and abortions. Using national registers, we used interrupted time-series modelling to compare outcomes of pregnancies conceived before and after a tax cut, resulting in 33% mean decrease of off-premise alcohol prices on 1 March 2004. We also addressed possible heterogeneity of the associations by maternal age and household income. Finland. All registered pregnancies starting 2 years before and 1 year after the alcohol price cut (analysis sample consisted of 169 735 live births and 32 441 abortions). The outcomes were birth weight, gestational age, the probability of low birth weight (< 2500 g at birth), preterm birth (< 37 weeks of gestation), any congenital malformations and share of registered abortions of pregnancies. On the population level, lowered alcohol prices were associated with an increase in abortions immediately after the price cut [+0.84 percentage points; 95% confidence interval (CI) = 0.2, 1.4]. For birth outcomes, negative associations were observed among women in the lowest income quintile; for example, increased probabilities of low birth weight (+1.5 percentage points; 95% CI = 0.4, 2.6) and preterm birth (+1.98 percentage points; 95% CI = 0.8, 3.2). All changes were strongest immediately after the price cut and attenuated during the course of the following year. Lowered alcohol prices in Finland were associated with a short-term increase in adverse birth outcomes among low-income mothers and an overall increase in abortions.

Parental educational similarity and inequality implications for infant health in Chile: Evidence from administrative records, 1990–2015

This study expands existing scholarship on the relationship between parental educational similarity and infant health using rich administrative data from Chile covering births that occurred between 1990 and 2015. We test the relationship between parental educational similarity ( homogamy ) or dissimilarity ( heterogamy ) and two measures of infant health, namely low birth weight (LBW) and preterm birth (PB). We show that parental educational homogamy is associated with a reduced probability of low birth weight and preterm birth – particularly at the high end of the educational distribution – and the observed association is only partly driven by selection into homogamous couples, as demonstrated by complementary quasi-experimental analyses conducted on a subsample of matched step-siblings from same mothers but different fathers. We further show that couples where women outrank men in educational attainment ( hypogamy ) exhibit worse birth outcomes relative to their homogamous and hypergamous counterparts. Municipality-level analyses merging external information on female labor force participation (FLFP) prior to childbirth reveal that the association between hypogamy and children’s outcomes is increasingly negative as FLFP increases, highlighting a strong work-life balance tension for highly-educated women who are actively engaged in the labor force. Insights from this study contribute to a better understanding of the inequality debate surrounding the intergenerational transmission of advantage and disadvantage – a topical issue in a country that has recently joined the rank of the world’s wealthiest nations yet maintains extreme levels of socioeconomic inequality. • Chile has recently joined the rank of the world’s wealthiest nations, yet it maintains extreme levels of socio-economic inequality and worsening infant health overtime • We explore whether the educational composition of couples – and their changing nature over time – bears any relationship with infant health using rich birth records from Chile • We leverage quasi-experimental methods to assuage endogeneity concerns related to selection into specific couple types • We find that couples where men and women hold the same level of education exhibit better infant health than couples where men and women hold different levels of education • However, couples where women outrank men in educational attainment exhibit worse birth outcomes relative to their homogamous and hypergamous counterparts • The latter finding is exacerbated in contexts characterized by higher female labor force participation

The effects of increasing income for vulnerable families: better birth outcomes, continued disparities

ABSTRACT Evidence suggests that cash transfers through the Earned Income Tax Credit (EITC) programme induce better birth outcomes. We use US Vital Statistics data for all births in Maryland from 1995–2004 to capture the casual effects of implementing a local EITC programme across households. Alternative difference-in-differences (DD) comparison groups compare treatment households with like households in non-EITC counties and ineligible households in the same county. We find that the implementation of the local EITC reduced the probability of low birth weight by as much as 3.5 percentage points for births to White and Black mothers with little evidence of an effect for Hispanic mothers. This reduction represents a 46% decrease for White mothers and 26% decrease for Black mothers. Despite improving average birth outcomes, EITC cash transfers did not reduce disparities in birth outcomes.

Does short-term, airborne lead exposure during pregnancy affect birth outcomes? Quasi-experimental evidence from NASCAR's deleading policy.

There is evidence of a weak placental-fetal barrier to lead, suggesting that maternal lead exposure could affect the fetus. The health consequences for newborns from in utero lead exposure are not well understood. We estimated the effects by trimester, of short-term (<1 week), airborne lead exposure during pregnancy on birth outcomes. We use quasi-experimental variation in airborne lead exposure during pregnancy, based on NASCAR's deleading of racing fuel in 2007, in a difference-in-differences model, to estimate the effect of deleading on the birth outcomes of all live births (n=147,673) in the Charlotte-Concord-Gastonia Metropolitan Statistical Area between 2004 and 2009. After deleading, children born to mothers residing <4000m of Charlotte Motor Speedway (relative to those residing >10,000m) experienced an average increase in birthweight (BW) of 102.50g [P<0.001]. The probability of low birthweight (LBW) declined by 0.045 [P=0.001], preterm (PRE) births by 0.03 [P=0.04], and small for gestational age (SGA) by 0.04 [P=0.002]. We find that benefits accrue primarily in preterm LBW and SGA babies, and from decreased lead exposure in the first trimester. Short-term exposure to airborne lead during pregnancy adversely affects birth outcomes. Reducing even very brief exposure to airborne lead during pregnancy may improve birth outcomes.

Racial Differences in the Association between the U.S. Earned Income Tax Credit and Birthweight.

We examined whether the largest U.S. poverty alleviation program for families, the Earned Income Tax Credit (EITC), has different associations with birthweight among women of different racial backgrounds. We analyzed data from the 1985-2015 waves of the Panel Study of Income Dynamics, a longitudinal cohort study of U.S. families (N=5,230 infants born to 3,672 women). The primary outcome was a continuous measure of birthweight, with secondary outcomes including low birthweight (LBW) and very LBW. Using rich sociodemographic data available in the Panel Study of Income Dynamics, we calculated the amount of EITC benefit for which women were eligible. We then examined the association of EITC benefit size with each outcome using multivariable regressions, examining the sample overall as well as racial subgroups (White, Black, or other). We found that larger EITC benefits were not associated with increased infant birthweight for the overall sample (18.37g per $1,000 of EITC; 95% confidence interval [CI], -2.62 to 33.36). There was an increase in birthweight for Black women (40.17g; 95% CI: 7.32 to 73.02), but not for White women (-1.86g; 95% CI, -33.33 to 29.60) or women of other races (-13.26g; 95% CI, -75.90 to 49.38). There was no association between EITC benefit size and the probability of LBW or very LBW. Results were robust to alternative model specifications. Social policies to address poverty may be effective at decreasing racial disparities in birthweight. Future work should examine potential mechanisms and the benefits of improved health outcomes for children later in life.

Development and validation of nomogram for prediction of low birth weight: a large-scale cross-sectional study in northwest China

Background Birth weight is closely related to infant survival and future health, growth and development. In developing countries, the incidence of low birth weight is twice as high as in developed countries. Due to the low economic and medical level in northwest China, the problem of low birth weight needs to be solved urgently. Methods We developed the predictive model based on data sets from a cross-sectional study conducted in northwest China, and data were collected from August 2013 to November 2013. A total of 27,233 patients were included in the study. Least Absolute Shrinkage and Selection Operator (LASSO) regression was used to select the optimal predictive characteristics among risk factors. The selected characteristics in the LASSO regression were used in multivariate logistic regression to build the prediction model. C-index and calibration plot were used to evaluate the degree of discrimination and calibration of the model. The decision curve is used to evaluate the net benefit rate of the application of the predictive tool. Bootstrapping validation was used for internal validation. Results Nomogram included gestational age, the sex of the attendance, the mother's education level, antenatal care, the mother's occupation, pregnancy-induced hypertension, family income, exposure to pesticides and nutritional supplements. The C-index of the predicted nomogram was 0.698(95% confidence interval: 0.671–0.725), C-index of internal verification was 0.694, indicating that the model had a good identification ability. Calibration plot showed that the model had good calibration. Decision curve indicated that patients with a threshold probability of low birth weight between 1% and 71% would benefit more from using the prediction tool. Conclusion The use of this predictive model will contribute to clinicians and pregnant women to make personalized predictions easily and quickly so that early lifestyle detection and medical intervention can be undertaken by physicians and patients.

Association of Elevated Maternal Serum Total Bile Acids With Low Birth Weight and Intrauterine Fetal Growth Restriction

Bile acids play essential roles in metabolic modulation. Excessive serum total bile acid (sTBA) levels during pregnancy are associated with adverse perinatal outcomes; however, their association with the risk of intrauterine growth restriction (IUGR) remains unclear. To investigate the association between maternal sTBA concentration during pregnancy and the risk of IUGR. This retrospective cohort study included pregnant individuals who delivered live singleton neonates and had regular antenatal examination records available at a hospital-based center in Shanghai, China, from 2014 to 2018. Data were analyzed from July to November 2020. Maternal sTBA concentration during pregnancy. Fetal birth weight and probability of low birth weight (LBW) and IUGR. This study included 68 245 singleton pregnancies with live births for analysis. The mean (SD) age of the pregnant individuals was 30.5 (3.8) years, 67 168 patients (98.4%) were Han, and 50 155 (73.5%) were nulliparous. Nonlinear regression models suggested that there was an inverted J-shaped association between maternal sTBA level during pregnancy and fetal birth weight, with a steep decrease in birth weight at high sTBA levels (estimated mean [SE] birth weight for sTBA of 40.8 ug/mL, 2879 [39.9] g) and greater birth weights at lower sTBA levels (estimated mean [SE] birth weight for sTBA 0.4 μg/mL, 3290 [3.9] g; and for 4.1 μg/mL, 3334 [1.6] g). Lower birth weight and a higher incidence of IUGR were observed in patients with gestational hypercholanemia (sTBA ≥4.08 μg/mL) compared with those without gestational hypercholanemia (birth weight: estimated adjusted mean [SE], 3309 [3.32] vs 3338 [0.80] g; P = .005; incidence of IUGR: 62 of 4467 [1.4%] vs 312 of 63 778 [0.5%]; P < .001). Moreover, compared with patients with sTBA concentrations of less than 4.08 μg/mL, those with gestational hypercholanemia had an increased risk of LBW (adjusted odds ratio [aOR], 1.29; 95% CI, 1.09-1.53) and IUGR (aOR, 2.18; 95% CI, 1.62-2.91). In addition, there was an additive interaction between hypertensive disorders in pregnancy (HDP) and hypercholanemia on LBW and IUGR risk. The highest risks of LBW and IUGR were found in pregnant individuals with both HDP and hypercholanemia compared with those with normotensive pregnancies with sTBA concentrations less than 4.08 μg/mL (LBW: aOR, 9.13; 95% CI, 6.88-12.12; IUGR: aOR, 19.14; 95% CI, 12.09-30.28). This study found that gestational hypercholanemia was associated with an increased risk of LBW and IUGR, especially in pregnant individuals with HDP. Therefore, it would be meaningful to monitor sTBA concentration during the follow-up of pregnancies with potential IUGR.

Maternal Adverse Childhood Experiences, Paternal Involvement, and Infant Health

To assess the interplay between maternal exposure to adverse childhood experiences (ACEs) and father's acknowledgment of paternity (AOP; a proxy for paternal involvement) in the risk of low birth weight (<2500 grams) and preterm birth (<37weeks) among offspring. Data come from the 2018 North Dakota and South Dakota Pregnancy Risk Assessment Monitoring System (n=1896). Logistic regression models were used to assess low birth weight and preterm birth outcomes. Moderation analyses are conducted to assess the interaction between maternal ACEs and father's AOP. Moderation analyses demonstrated a positive interaction between an accumulating number of maternal ACEs and being unmarried without AOP for low birth weight and preterm birth. Upon comparing newborns of unmarried women without AOP, those whose mothers were exposed to 4 or more ACEs had a 3.74 times greater probability of low birth weight (0.050 vs 0.187) and a 1.74 times greater probability of preterm birth (0.085 vs 0.148) than those whose mothers reported no ACE exposure. Exposure to accumulating ACEs substantially increases the risk of deleterious infant health outcomes, but only for newborns of unmarried women without AOP. Future research should assess the efficacy of interventions that can mitigate the impact of maternal ACEs in the absence of father's AOP.

Temperature, climate change, and birth weight: evidence from Hungary

We analyze the impact of in utero temperature exposure on the birth weight and an indicator for low birth weight using administrative data on singleton live births conceived between 2000 and 2016 in Hungary. We find that exposure to high temperatures during pregnancy decreases birth weight, but its impact on the probability of low birth weight is weaker. Exposure to one additional hot day (mean temperature > 25 °C) during the gestation period reduces birth weight by 0.46 g, relative to a 15–20 °C day. The second and third trimesters appear to be slightly more sensitive to temperature exposure than the first trimester. We project that climate change will decrease birth weight and increase the prevalence of low birth weight by the mid-twenty-first century. The projected impacts are the strongest for newborns conceived during the winter and spring months.

Going Beneath the Surface: Petroleum Pollution, Regulation, and Health

This paper quantifies the health impacts of petroleum leaks from underground storage tanks, the effectiveness of tank regulation, and the role of information as a policy tool in the same setting. Exposure to a leaking underground storage tank during gestation increases both the probability of low birthweight and preterm birth by 7–8 percent. Compliance with regulations requiring the adoption of preventative technologies mitigated the entire effect of leak exposure on low birthweight, and information increased avoidance and moving among highly educated mothers. Back-of-the-envelope calculations suggest the health benefits of preventative regulations exceed the upgrade cost to facilities. (JEL I12, K32, L71, L78, Q35, Q51, Q53)

Prevalence of and socioeconomic gradient in low birth weight in Ethiopia: further analysis of the 2016 demographic and health survey data

BackgroundEvidence suggests appearance of socioeconomic gradient in the probability of low birth weight (LBW). Such evidence, however, is scanty in Ethiopia. The study aimed to examine the prevalence of and socioeconomic gradient in LBW in Ethiopia.MethodData for the study were drawn from the Ethiopia Demographic and Health Survey conducted in 2016. The 2016 EDHS is the fourth wave in the series of nationally representative household surveys carried out in the country to deliver up-to-date health and demographic indicators for the Ethiopian population. Women aged 15 to 49 years were the main focus of the survey, with data also gathered from men aged 15 to 59 years and under five children. The study pursued complex sampling strategy to draw samples representative at national as well as at urban and rural levels. The data are available to the public domain and were accessed from the MEASURE DHS following registration. Multivariable logistic regression model and marginal standardization were used to estimate socioeconomic gradient in the probability of LBW. We performed sensitivity analysis to evaluate variation of LBW according to different categories of socioeconomic position. Maternal education and household wealth were used as measures of the socioeconomic position in the study.Results13.2% (95% confidence interval = 10.73, 15.65) of births were complicated by LBW. The findings showed that socioeconomic gradient was evident between maternal education and LBW; as education increases from no education to secondary education, the probability of occurrence of LBW consistently declined. However, no gradient in LBW was detected for household wealth.ConclusionsWe have identified education gradient in LBW, with the highest burden of LBW occurring among the non-educated women. To redress the observed education disparity in LBW, targeted interventions need to be implemented with greater emphasis placed on illiterate women.

Determinants of birth weight among children of irregular migrant Venezuelan women in Barranquilla and Riohacha

To describe the determinants of birth weight in the children of Venezuelan women in irregular migration status during pregnancy, in Barranquilla and Riohacha, between 2018 and 2019. We carried out a longitudinal and descriptive study of secondary source, with a hospital and community basis. We included mother-child pairs of Venezuelan women in an irregular condition whose delivery occurred in Barranquilla and Riohacha between July 2018 and December 2019 (n=563). Results: We found a significative association between the number of prenatal care and low birth weight. The odds of being born with low birth weight among those who had no controls was 4.0 times in relation to those who met at least 4 controls during pregnancy (OR = 4.0, 95% CI 1.5 - 10.4). The probability of low birth weight in the newborns of those mothers who did not have prenatal controls was 82.7% higher compared to the children of mothers who had four or more prenatal cares.

Ethnicity and Low Birth Weight: Inequalities Between Ethnic Minorities and the Predominant Mestizo Population, Colombia, 2008-2014.

Low birth weight (LBW) is a global problem that annually affects nearly 20 million children, 96% of these in developing countries. According to the WHO, the poorest and the ethnic minorities are the groups most affected by this indicator. A cross-sectional study of the database of all newborns officially registered in Colombia in 2008-2014 was done. While dichotomizing the mestizo population and ethnic minorities (Afro-descendants, indigenous, ROM), normal and low birth weight was used as the dependent variable and ethnicity as the explanatory variable. Other variables of the parents and the newborns were used as covariates. To assess associations, bivariate and multivariate logistic regression analyses were performed. The incidence of LBW among newborns registered in Colombia fluctuated at around 9%. Among the ethnic minorities, the probability of LBW, adjusted for other variables, was significantly higher (OR 1.07, 95% CI 1.05-1.08) than among mestizos. A significantly higher risk of LBW to newborns in the ethnic minorities' group, and those with unfavorable socioeconomic conditions, was found.

Wildfire and infant health: a geospatial approach to estimating the health impacts of wildfire smoke exposure

ABSTRACT We estimate the effects of wildfire smoke exposure on infant health. Exposure to wildfire smoke is determined using the latitude and longitude coordinates corresponding to each infant’s home address and a fine-scaled spatial dataset of wildfire smoke plumes constructed in GIS from satellite images of the landscape. Using a difference-in-differences estimation strategy, model estimates show that exposure to wildfire smoke leads to a .034 increase in the probability of low birthweight.

Lead in Drinking Water and Birth Outcomes: A Tale of Two Water Treatment Plants

The recent drinking water crisis in Newark, New Jersey's largest city, has renewed concerns about the lead-in-water crisis becoming a persistent and widespread problem owing to the nation's aging infrastructure. We exploit a unique natural experiment in Newark, which exogenously exposed some women in the city to higher levels of lead in tap water but not others, to identify a causal effect of prenatal lead exposure on fetal health. Using birth data that contain information on mothers' exact residential addresses, we find robust and consistent evidence that prenatal exposure to lead significantly raises the probability of low birth weight or preterm births by approximately 1.4 to 1.9 percentage points (14-22 percent), and the adverse effects are largely concentrated among mothers of lower socioeconomic status. Our findings have important policy implications in light of the long-term impact of compromised health at birth and the substantial number of lead water pipes that remain in use as part of our aging infrastructure. Institutional subscribers to the NBER working paper series, and residents of developing countries may download this paper without additional charge at www.nber.org.

EARNED INCOME TAX CREDITS AND INFANT HEALTH

In 1998, Montgomery County, Maryland adopted a local earned income tax credit (EITC) program. We use U.S. Vital Statistics data covering births in Maryland from 1995 to 2004 to examine whether the local EITC impacted birth weight and the probability of low birth weight in Montgomery County. Using difference-in-differences (DD) and triple differences (DDD) strategies, we find that the Montgomery County EITC decreased the probability of low birth weight by 1.9 to 2.4 percentage points among likely eligible mothers. Using the local credit as a unique opportunity to identify EITC effects within a state, these estimates contribute to a growing body of literature that finds improved birth outcomes for credit recipients.

Association between serum estradiol level on the human chorionic gonadotrophin administration day and clinical outcome.

Background:Estradiol, as an important hormone in follicular development and endometrial receptivity, is closely related to clinical outcomes of fresh in vitro fertilization embryo transfer (IVF-ET) cycles. The aim of this retrospective study was to evaluate the association between elevated serum estradiol (E2) levels on the day of human chorionic gonadotrophin (hCG) administration and IVF-ET pregnancy and birth outcomes.Methods:A total of 1771 infertile patients with their first fresh IVF-ET cycles were analyzed retrospectively between January 2011 and January 2016 in Peking University First Hospital. Patients were categorized by serum E2 levels on the day of hCG administration into six groups: group 1 (serum E2 levels ≤ 1000 pg/mL, n = 205), group 2 (serum E2 levels 1001–2000 pg/mL, n = 457), group 3 (serum E2 levels 2001–3000 pg/mL, n = 425), group 4 (serum E2 levels 3001–4000 pg/mL, n = 310), group 5 (serum E2 levels 4001–5000 pg/mL, n = 237), and group 6 (serum E2 levels > 5000 pg/mL, n = 137). The retrieved oocyte and MII oocyte numbers and implantation and clinical pregnancy rates of the groups were compared as the first objective of the study. For the 360 women with singleton births among all patients, the area under the corresponding receiver operating characteristic curve (ROC curve) was calculated to assess the predictive value of the E2 change for the probability of low birth weight (LBW) infants as the second objective.Results:The retrieved oocyte and MII oocyte numbers and implantation and clinical pregnancy rates gradually increased from groups 1 to 5 but decreased in group 6. The parameters of group 1 were statistically worse than those of the other groups, from group 2 to group 6 (the number of retrieved oocytes, t = 13.096, t = 23.307, t = 23.086, t = 26.376, t = 19.636, P < 0.003; the number of retrieved MII oocytes, t = 10.856, t = 20.868, t = 21.874, t = 23.374, t = 19.092, P < 0.003; the implantation rate, χ2 = 12.179, χ2 = 22.239, χ2 = 23.993, χ2 = 23.344, χ2 = 16.758, P < 0.003; the clinical pregnancy rate, χ2 = 16.415, χ2 = 28.074, χ2 = 35.387, χ2 = 37.025, χ2 = 24.590, P < 0.003). ROC analysis revealed that when a serum peak E2 of 3148 pg/mL was used to predict LBW.Conclusions:The results indicate that serum E2 levels have a concentration-dependent effect on clinical outcomes. The optimal range of the E2 level during a fresh IVF-ET cycle is 1000 to 3148 pg/mL.