Pregnant women with COVID-19 and risk of adverse birth outcomes and maternal-fetal vertical transmission: a population-based cohort study in Wuhan, China

Abstract Background The coronavirus disease 2019 (COVID-19) outbreak is evolving rapidly worldwide. However, little is known about the association between pregnant women with COVID-19 and the risk of adverse birth outcomes. Method We conducted a retrospective cohort study based on the Maternal and Child Health Information System (MCHIMS) of Wuhan, China. All pregnant women with singleton live birth recorded by the system between January 13 and March 18, 2020, were included. The adverse birth outcomes were preterm birth, low birth weight, neonatal asphyxia, premature rupture of membrane (PROM), and cesarean section delivery. Multivariate logistic regression was used to evaluate the associations between maternal COVID-19 diagnosis and adverse birth outcomes. Results Out of 11,078 pregnant women, 65 were confirmed with coronavirus disease 2019 (COVID-19). No deaths occurred from these confirmed cases or their newborns. Compared to pregnant women without COVID-19, pregnant women with a confirmed COVID-19 diagnosis had an increased risk of preterm birth (OR 3.34, 95% CI 1.60–7.00) and cesarean section (OR 3.63, 95% CI 1.95–6.76). There was no statistical difference in low birth weight, neonatal asphyxia, and PROM between the mothers with and without COVID-19. Among these newborns that were born to mothers with confirmed COVID-19, none was tested severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive or had abnormal CT results. Only one had diarrhea and three had a fever. Conclusions This population-based cohort study suggests that COVID-19 during the later pregnancy is associated with an increased risk of adverse birth outcomes, including iatrogenic preterm birth and cesarean section delivery. Our data provide little evidence for maternal-fetal vertical transmission of SARS-CoV-2. It is important to monitor the long-term health effects of SARS-CoV-2 infection on pregnant women and their children.

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Comparison of adverse perinatal outcomes between Asians and Caucasians: a population-based retrospective cohort study in Ontario

BMC Pregnancy and Childbirth ◽

10.1186/s12884-020-03467-w ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Na Zeng ◽

Erica Erwin ◽

Wendy Wen ◽

Daniel J. Corsi ◽

Shi Wu Wen ◽

...

Keyword(s):

Cohort Study ◽

Birth Weight ◽

Preterm Birth ◽

Cesarean Section ◽

Gestational Age ◽

Retrospective Cohort Study ◽

Retrospective Cohort ◽

Perinatal Outcomes ◽

Population Based ◽

Adverse Perinatal Outcomes

Abstract Background Racial disparities in adverse perinatal outcomes have been studied in other countries, but little has been done for the Canadian population. In this study, we sought to examine the disparities in adverse perinatal outcomes between Asians and Caucasians in Ontario, Canada. Methods We conducted a population-based retrospective cohort study that included all Asian and Caucasian women who attended a prenatal screening and resulted in a singleton birth in an Ontario hospital (April 1st, 2015-March 31st, 2017). Generalized estimating equation models were used to estimate the independent adjusted relative risks and adjusted risk difference of adverse perinatal outcomes for Asians compared with Caucasians. Results Among 237,293 eligible women, 31% were Asian and 69% were Caucasian. Asians were at an increased risk of gestational diabetes mellitus, placental previa, early preterm birth (< 32 weeks), preterm birth, emergency cesarean section, 3rd and 4th degree perineal tears, low birth weight (< 2500 g, < 1500 g), small-for-gestational-age (<10th percentile, <3rd percentile), neonatal intensive care unit admission, and hyperbilirubinemia requiring treatment, but had lower risks of preeclampsia, macrosomia (birth weight > 4000 g), large-for-gestational-age neonates, 5-min Apgar score < 7, and arterial cord pH ≤7.1, as compared with Caucasians. No difference in risk of elective cesarean section was observed between Asians and Caucasians. Conclusion There are significant differences in several adverse perinatal outcomes between Asians and Caucasians. These differences should be taken into consideration for clinical practices due to the large Asian population in Canada.

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Febrile Rhinovirus Illness During Pregnancy Is Associated With Low Birth Weight in Nepal

Open Forum Infectious Diseases ◽

10.1093/ofid/ofx073 ◽

2017 ◽

Vol 4 (2) ◽

Cited By ~ 6

Author(s):

Erin K Philpott ◽

Janet A Englund ◽

Joanne Katz ◽

James Tielsch ◽

Subarna Khatry ◽

...

Keyword(s):

Birth Weight ◽

Infant Mortality ◽

Low Birth Weight ◽

Pregnant Women ◽

Birth Outcomes ◽

Febrile Illness ◽

Respiratory Illness ◽

Adverse Birth Outcomes ◽

Increased Risk ◽

Febrile Respiratory Illness

Abstract Background Adverse birth outcomes, including low birth weight (LBW), defined as <2500 grams, small-for-gestational-age (SGA), and prematurity, contribute to 60%–80% of infant mortality worldwide and may be related to infections during pregnancy. The aim of this study was to assess whether febrile human rhinovirus (HRV) illness is associated with adverse birth outcomes. Methods Active household-based weekly surveillance was performed for respiratory illness episodes in pregnant women as part of a community-based, prospective, randomized trial of maternal influenza immunization in rural Nepal. Rhinovirus (HRV) febrile illness episodes were defined as fever plus cough, sore throat, runny nose, and/or myalgia with HRV detected on mid-nasal swab. Multivariate regression analysis evaluated the association between febrile HRV respiratory illness and adverse birth outcomes. Results Overall, 96 (3%) of 3693 pregnant women had HRV-positive febrile respiratory illnesses. Infants born to pregnant women with HRV febrile illness had a 1.6-fold increased risk of being LBW compared with those with non-HRV febrile illness (28 of 96 [38%] vs 109 of 458 [24%]; relative risk [RR], 1.6; 95% confidence interval [CI], 1.1–2.3). No difference in risk of LBW was observed between infants born to mothers with non-HRV febrile respiratory illness and those without respiratory illness during pregnancy (109 of 458 [24%] vs 552 of 2220 [25%], respectively; RR, 1.0; 95% CI, 0.8–1.2). Conclusions Febrile illness due to rhinovirus during pregnancy was associated with increased risk of LBW in a rural South Asian population. Interventions to reduce the burden of febrile respiratory illness due to rhinovirus during pregnancy may have a significant impact on LBW and subsequent infant mortality.

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COVID-19 Lockdown Increased the Risk of Preterm Birth

Frontiers in Medicine ◽

10.3389/fmed.2021.705943 ◽

2021 ◽

Vol 8 ◽

Author(s):

Ting-ting Lin ◽

Chen Zhang ◽

Lei Chen ◽

Li Jin ◽

Xian-hua Lin ◽

...

Keyword(s):

Cohort Study ◽

Preterm Birth ◽

Pregnant Women ◽

Population Based ◽

Second Trimester ◽

Spontaneous Preterm Birth ◽

Third Trimester ◽

Very Preterm ◽

Increased Risk ◽

The City

Purpose: To estimate whether the city-specific lockdown in Shanghai induced by the COVID-19 pandemic affected preterm birth rates among uninfected pregnant women in different trimesters.Methods: The population-based retrospective cohort study was conducted in the International Peace Maternity and Child Health Hospital (IPMCH) in Shanghai, China. Pregnant women without COVID-19 received perinatal healthcare during lockdown (from January 24, 2020 to March 24, 2020) and non-lockdown (from January 24, 2019 to March 24, 2019) period and giving birth to a live infant at IPMCH were enrolled. 1:1 propensity score matching and Inverse probability of treatment weighting were used to evaluate preterm birth (<37 weeks), very preterm birth (<34 weeks), preterm birth with premature rupture of membranes (PROM-PTB), spontaneous preterm birth with intact membranes (S-PTB), and medically induced preterm birth (MI-PTB) between two groups.Results: 8,270 pregnant women were in the lockdown group, and 9,815 were in the non-lockdown group. Pregnant women in second trimester during lockdown had a higher risk of PTB than those during the non-lockdown period [OR: 1.43 (CI 1.01–2.02), ARD: 1.7% (CI 0.04–3.4%), p = 0.045]. Furthermore, pregnant women in third trimester during lockdown had a higher risk of PROM-PTB than those during the non-lockdown period [OR: 1.64 (CI 1.09–2.47), ARD: 0.9% (CI 0.2–1.6%), p = 0.02]; no group differences were found related to rates of VPTB, S-PTB or MI-PTB.Conclusion: In this cohort study in China, we found that there was an increased risk in preterm birth for non-infected women in COVID-19 lockdown who were in their second trimester.

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Maternal exposure to low-to-medium altitude and birth outcomes: evidence from a population-based study in Chinese newborns

Journal of Developmental Origins of Health and Disease ◽

10.1017/s204017442000063x ◽

2020 ◽

pp. 1-9

Author(s):

Binyan Zhang ◽

Wentao Wu ◽

Guoshuai Shi ◽

Baibing Mi ◽

Fangyao Chen ◽

...

Keyword(s):

Birth Weight ◽

Linear Relationship ◽

Birth Outcomes ◽

Gestational Age ◽

Population Based ◽

Adverse Birth Outcomes ◽

Cross Sectional Survey ◽

Altitude Effect ◽

Cross Sectional ◽

Increased Risk

Abstract Despite high altitude was implicated in adverse birth outcomes, there remained a paucity of evidence on low-to-medium altitude effect. This study aimed to explore the association of low-to-medium altitude with birth outcomes. A population-based cross-sectional survey was performed using a stratified multistage random sampling method among women with their infants born during 2010–2013 in Northwestern China. Altitude was determined in meters based on the village or community of the mother’s living areas. Birth outcomes involved birth weight, gestational age, and small for gestational age (SGA). Generalized linear models were fitted to investigate the association of altitude with birth outcomes. Moreover, the dose–response relationship between altitude and birth outcomes was evaluated with a restricted cubic spline function. A total of 27 801 women with their infants were included. After adjusting for potential confounders, every 100-m increase in the altitude was associated with reduced birth weight by 6.4 (95% CI −8.1, −4.6) g, the slight increase of gestational age by 0.015 (95% CI 0.010, 0.020) week, and an increased risk of SGA birth (odds ratio 1.03, 95% CI 1.02, 1.04). Moreover, there was an inversely linear relationship between altitude and birth weight (P for overall < 0.001 and P for nonlinear = 0.312), and a positive linear relationship between altitude and SGA (P for overall < 0.001 and P for nonlinear = 0.194). However, a nonlinear relationship was observed between altitude and gestational age (P for overall < 0.001 and P for nonlinear = 0.010). The present results suggest that low-to-medium altitude is possibly associated with adverse birth outcomes.

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Dietary iron and calcium intakes during pregnancy are associated with lower risk of prematurity, stillbirth and neonatal mortality among women in Tanzania

Public Health Nutrition ◽

10.1017/s1368980016002809 ◽

2016 ◽

Vol 20 (4) ◽

pp. 678-686 ◽

Cited By ~ 9

Author(s):

Dominic Mosha ◽

Enju Liu ◽

Ellen Hertzmark ◽

Grace Chan ◽

Christopher Sudfeld ◽

...

Keyword(s):

Preterm Birth ◽

Dietary Intake ◽

Pregnant Women ◽

Neonatal Mortality ◽

Birth Outcomes ◽

Perinatal Care ◽

Adverse Outcomes ◽

Adverse Birth Outcomes ◽

Increased Risk ◽

Reduced Risk

AbstractObjectivePrematurity, stillbirth and other adverse birth outcomes remain major concerns in resource-limited settings. Poor dietary intake of micronutrients during pregnancy has been associated with increased risk of adverse outcomes. We determined the relationships between dietary Fe and Ca intakes during pregnancy and risks of adverse birth outcomes among HIV-negative women.DesignWomen’s diet was assessed through repeated 24 h diet recalls in pregnancy. Mean intakes of total Fe, Fe from animal sources and Ca during pregnancy were examined in relation to adverse birth outcomes and neonatal mortality. Women were prescribed daily Fe supplements as per standard perinatal care.SettingDar es Salaam, Tanzania.SubjectsA cohort of 7634 pregnant women.ResultsMedian (interquartile range) daily dietary intake of total Fe, animal Fe and Ca was 11·9 (9·3–14·7), 0·5 (0–1·1) and 383·9 (187·4–741·2) mg, respectively. Total Fe intake was significantly associated with reduced risk of stillbirth (trend over quartiles, P=0·010). Animal Fe intake was significantly associated with reduced risk of preterm birth and extreme preterm birth. Animal Fe intake was inversely related to neonatal mortality risk; compared with women in the lowest intake quartile, those in the top quartile were 0·51 times as likely to have neonatal death (95 % CI 0·33, 0·77). Higher Ca intake was associated with reduced risk of preterm birth (relative risk; 95 % CI: 0·76; 0·65, 0·88) and extreme preterm birth (0·63; 0·47, 0·86). Women in the highest Ca intake quartile had reduced risk of neonatal mortality (0·59; 0·37, 0·92).ConclusionsDaily dietary Fe and Ca intakes among pregnant women are very low. Improvement of women’s diet quality during gestation is likely to improve the risks of adverse birth outcomes.

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Advanced Maternal Age and Adverse Maternal and Neonatal Outcomes in Pregnant Women

Current Women s Health Reviews ◽

10.2174/1573404816999201009160848 ◽

2020 ◽

Vol 16 ◽

Author(s):

Reza Omani-Samani ◽

Saman Maroufizadeh ◽

Nafise Saedi ◽

Nasim Shokouhi ◽

Arezoo Esmailzadeh ◽

...

Keyword(s):

Birth Weight ◽

Preterm Birth ◽

Low Birth Weight ◽

Cesarean Section ◽

Pregnant Women ◽

Maternal Age ◽

Unwanted Pregnancy ◽

Advanced Maternal Age ◽

Neonatal Outcomes ◽

Maternal And Neonatal Outcomes

Background: Advanced maternal age is an important predictor for maternal and neonatal outcomes such as maternal mortality, low birth weight, stillbirth, preterm birth, cesarean section and preeclampsia. Objective: To determine the association of advanced maternal age and adverse maternal and neonatal outcomes in Iranian pregnant women. Methods: In this hospital-based cross-sectional study, 5117 pregnant women from 103 hospitals in Tehran, Iran, were participated in the study in 2015. The required data were gathered from hospitals which equipped to the department of obstetrics and gynecology. Advanced maternal age was considered as an independent variable and unwanted pregnancy, preeclampsia, preterm birth, cesarean section and low birth weight were considered as interested outcomes. Results: In our study, the prevalence of advanced maternal age was 12.08%. Advanced maternal age was significantly associated with higher risk of unwanted pregnancy (OR: 1.39, 95% CI: 1.12-1.73), preterm birth (OR: 1.75, 95% CI: 1.28- 2.39) and cesarean section (OR: 1.34, 95% CI: 1.03-1.74). In our study, there was no significant relationship between advanced maternal age and preeclampsia but this relationship could be clinically important (OR: 1.48, 95% CI: 0.99-2.20, P=0.052), and there is no significant relationship between advanced maternal age and low birth weight (OR: 1.08, 95% CI: 0.67-1.74, P=0.736). Conclusion: Advanced maternal age is associated with higher risk of unintended pregnancy, preterm birth and cesarean section but our findings did not support advanced maternal age as a risk factor associated with low birth weight.

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Mass incarceration and public health: the association between black jail incarceration and adverse birth outcomes among black women in Louisiana

BMC Pregnancy and Childbirth ◽

10.1186/s12884-019-2690-z ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 1

Author(s):

Lauren Dyer ◽

Rachel Hardeman ◽

Dovile Vilda ◽

Katherine Theall ◽

Maeve Wallace

Keyword(s):

Birth Weight ◽

Preterm Birth ◽

Black Women ◽

Low Birth Weight ◽

Racial Disparities ◽

Population Health ◽

Birth Outcomes ◽

Mass Incarceration ◽

Interquartile Range ◽

Adverse Birth Outcomes

Abstract Background A growing body of evidence is beginning to highlight how mass incarceration shapes inequalities in population health. Non-Hispanic blacks are disproportionately affected by incarceration and criminal law enforcement, an enduring legacy of a racially-biased criminal justice system with broad health implications for black families and communities. Louisiana has consistently maintained one of the highest rates of black incarceration in the nation. Concurrently, large racial disparities in population health persist. Methods We conducted a cross-sectional analysis of all births among non-Hispanic black women in Louisiana in 2014 to identify associations between parish-level (county equivalent) prevalence of jail incarceration within the black population and adverse birth outcomes (N = 23,954). We fit a log-Poisson model with generalized estimating equations to approximate the relative risk of preterm birth and low birth weight associated with an interquartile range increase in incarceration, controlling for confounders. In sensitivity analyses, we additionally adjusted for the parish-level index crime prevalence and analyzed regression models wherein white incarceration was used to predict the risk of adverse birth outcomes in order to quantify the degree to which mass incarceration may harm health above and beyond living in a high crime area. Results There was a significant 3% higher risk of preterm birth among black women associated with an interquartile range increase in the parish-level incarceration prevalence of black individuals, independent of other factors. Adjusting for the prevalence of index crimes did not substantively change the results of the models. Conclusion Due to the positive significant associations between the prevalence of black individuals incarcerated in Louisiana jails and estimated risk of preterm birth, mass incarceration may be an underlying cause of the persistent inequities in reproductive health outcomes experienced by black women in Louisiana. Not only are there economic and social impacts stemming from mass incarceration, but there may also be implications for population health and health inequities, including the persistence of racial disparities in preterm birth and low birth weight.

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Prenatal electrocardiogram testing and postpartum depression: A population-based cohort study

Obstetric Medicine ◽

10.1177/1753495x211012502 ◽

2021 ◽

pp. 1753495X2110125

Author(s):

Jonathan S Zipursky ◽

Deva Thiruchelvam ◽

Donald A Redelmeier

Keyword(s):

Cohort Study ◽

Postpartum Depression ◽

Pregnant Women ◽

Odds Ratio ◽

Population Based ◽

Relative Increase ◽

Organic Disease ◽

Increased Risk ◽

Clinical Clue ◽

In Pregnancy

Background Cardiovascular symptoms in pregnancy may be a clue to psychological distress. We examined whether electrocardiogram testing in pregnant women is associated with an increased risk of subsequent postpartum depression. Methods We conducted a population-based cohort study of pregnant women who delivered in Ontario, Canada comparing women who received a prenatal ECG to women who did not. Results In total, 3,238,218 women gave birth during the 25-year study period of whom 157,352 (5%) received an electrocardiogram during prenatal care. Receiving an electrocardiogram test was associated with a one-third relative increase in the odds of postpartum depression (odds ratio 1.34; 95% confidence interval 1.29–1.39, p < 0.001). Conclusion The association between prenatal electrocardiogram testing and postpartum depression suggests a possible link of organic disease with mental illness, and emphasizes that cardiovascular symptoms may be a clinical clue to the presence of an underlying mood disorder.

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Maternal exposure to airborne polychlorinated biphenyls (PCBs) and risk of adverse birth outcomes

European Journal of Epidemiology ◽

10.1007/s10654-021-00793-x ◽

2021 ◽

Author(s):

Ane Bungum Kofoed ◽

Laura Deen ◽

Karin Sørig Hougaard ◽

Kajsa Ugelvig Petersen ◽

Harald William Meyer ◽

...

Keyword(s):

Birth Weight ◽

Preterm Birth ◽

Sex Ratio ◽

Polychlorinated Biphenyls ◽

Birth Outcomes ◽

Gestational Age ◽

Small For Gestational Age ◽

Maternal Exposure ◽

Adverse Birth Outcomes ◽

Secondary Sex Ratio

AbstractHuman health effects of airborne lower-chlorinated polychlorinated biphenyls (LC-PCBs) are largely unexplored. Since PCBs may cross the placenta, maternal exposure could potentially have negative consequences for fetal development. We aimed to determine if exposure to airborne PCB during pregnancy was associated with adverse birth outcomes. In this cohort study, exposed women had lived in PCB contaminated apartments at least one year during the 3.6 years before conception or the entire first trimester of pregnancy. The women and their children were followed for birth outcomes in Danish health registers. Logistic regression was performed to estimate odds ratios (OR) for changes in secondary sex ratio, preterm birth, major congenital malformations, cryptorchidism, and being born small for gestational age. We performed linear regression to estimate difference in birth weight among children of exposed and unexposed mothers. All models were adjusted for maternal age, educational level, ethnicity, and calendar time. We identified 885 exposed pregnancies and 3327 unexposed pregnancies. Relative to unexposed women, exposed women had OR 0.97 (95% CI 0.82, 1.15) for secondary sex ratio, OR 1.13 (95% CI 0.76, 1.67) for preterm birth, OR 1.28 (95% CI 0.81, 2.01) for having a child with major malformations, OR 1.73 (95% CI 1.01, 2.95) for cryptorchidism and OR 1.23 (95% CI 0.88, 1.72) for giving birth to a child born small for gestational age. The difference in birth weight for children of exposed compared to unexposed women was − 32 g (95% CI—79, 14). We observed an increased risk of cryptorchidism among boys after maternal airborne LC-PCB exposure, but due to the proxy measure of exposure, inability to perform dose–response analyses, and the lack of comparable literature, larger cohort studies with direct measures of exposure are needed to investigate the safety of airborne LC-PCB exposure during pregnancy

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O-221 Stage and morphology of the competent blastocyst are associated with pregnancy and birth outcomes; a multicenter cohort study

Human Reproduction ◽

10.1093/humrep/deab128.045 ◽

2021 ◽

Vol 36 (Supplement_1) ◽

Author(s):

M L Groendahl ◽

M. Buhl Borgstrøm ◽

U. Schiøler Kesmodel

Keyword(s):

Cohort Study ◽

Birth Weight ◽

Preterm Birth ◽

Birth Outcomes ◽

Gestational Age ◽

Blastocyst Transfer ◽

Singleton Pregnancy ◽

Child Weight ◽

Single Blastocyst Transfer ◽

Pregnancy And Birth

Abstract Study question Do stage and morphology of the competent blastocyst associate with initial hCG rise, gestational age, preterm birth, child birth weight, length, and child sex? Summary answer Higher stage, TE- and ICM-scores associated with higher hCG-rise; ICM- and TE-scores associated with length at birth, and higher stage and TE-score associated with boys. What is known already Many studies have focused on the developmental stage and morphology of the blastocysts in order to find biomarkers of competence to improve the efficacy of assisted reproduction technology treatment. In contrast, the associations between blastocyst assessment score parameters (individually or by combined score) and perinatal outcome have only been reported in few and smaller single center studies, and conflicting results have been presented. In the present study, we focused on the in vitro cultured blastocyst leading to a live birth and how the stage and morphology of these competent blastocysts relate to implantation and birth outcomes. Study design, size, duration Multicenter historical cohort study based on exposure (blastocyst stage (1-6) and morphology (trophectoderm (TE) and inner cell mass (ICM): A,B,C)) and outcome data (serum human chorionic gonadotrophin (hCG), gestational age, preterm birth, child weight, length, and sex) from women undergoing single blastocyst transfer resulting in singleton pregnancy and birth. Data from 16 private and university-based facilities for clinical services and research from 2014 to 2018 was included. Participants/materials, setting, methods 7246 women, who underwent ovarian stimulation or Frozen-thawed-Embryo-Transfer with single blastocyst transfer resulting in singleton pregnancy were identified. Linking to the Danish Medical Birth Registry resulted in a total of 4842 women with live birth being included. Initial serum hCG value (IU/L) (11 days after transfer), gestational age (days), preterm birth (%) child weight (grams), length (cm) and sex. The analyses were adjusted for female age, BMI, smoking, center, diagnosis, parity, gestational age and sex. Main results and the role of chance Higher mean initial hCG was consistently positively associated with higher developmental stage (p < 0.001), TE (p < 0.001) and ICM score (p = 0.02); for stage 6, TE (A) and ICM (A): 508.4, 436.5 and 428.5 IU/L, respectively. No differences between blastocyst morphology (stage, TE, ICM), gestational age (mean 276.6 days), preterm birth (8.3%) and birth weight (mean 3461.7 gram) were statistically significant. While stage showed no association with length at birth (mean 51.6 cm), length at birth between blastocysts with a TE score C and a TE score A were statistically significant (mean difference 0.5 cm (0.07;0.83)) as was the length at birth between blastocysts with an ICM score B and C compared to score A, mean differences respectively 0.2 cm (0.02;0.31) and 0.5 cm (0.03;0.87). Stage and TE, but not ICM were associated with the sex of the child. Blastocysts transferred with stage score 5 compared to blastocysts transferred with score 3 had a 33% increased probability of being a boy (OR 1.33 (1.08;1.64)). Further, TE score B blastocysts compared to TE score A blastocysts had a 28% reduced probability of being a boy (OR 0.72 (0.62;0.82)). Limitations, reasons for caution The assessment scores of the blastocystś stage and morphology were based on subjective evaluation, and information bias may have influenced the results. By adjusting for center, we took the potential variation in scoring between clinics into considerations. Wider implications of the findings Stage and morphology of the competent blastocyst was associated with initial hCG rise suggesting an effect on implantation, which may be used in routine, everyday information to women and couples on the day of blastocyst transfer. Trial registration number j.nr.: VD-2018-282

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