The relationship between fetal gender and pregnancy outcome

Same disease - different effect: maternal diabetes impact on birth weight stratified by fetal sex

BACKGROUND

Male-sex is an independent risk factor for adverse perinatal outcomes. One example is gestational diabetes mellitus (GDM), which is associated with large gestational age neonates. It was previously described that fetal glucose metabolism is affected by fetal sex.

PURPOSE

To examine whether the birth weight of neonates is affected differently by GDM according to fetal sex.

METHODS

A retrospective normalized cohort analysis, using the open database of 2017 Natality Data from the National Vital Statistics System in the US. We compared the delta in neonatal birth weight, according to fetal sex, between pregnancies with or without GDM. Linear regression was used to take into consideration the effect of multiple confounders. For evaluation whether fetal sex is an independent risk factor for macrosomia (> 4000 and > 4500 g) following pregnancies complicated by GDM we used multivariate logistic regression.

RESULTS

A significant relationship was found between the sex of the neonate and the delta in birth weight associated with GDM (P-value < 0.0001). The average weight gain in neonates to GDM pregnancies was 71 g in females, and 56 g in males. The prevalence of macrosomia above 4000 g and 4500 g that was attributed to GDM was higher in female-sex neonates compared to male-sex neonates (P < 0.05).

CONCLUSION

According to our study results, female sex is associated with higher fetal weight gain in pregnancies complicated by GDM. Moreover, macrosomia's rate (> 4000 g and > 4500 g) attributed to GDM raised in a more significant manner in female-sex neonates.

Sex differences in microRNA expression in first and third trimester human placenta†

Maternal and fetal pregnancy outcomes related to placental function vary based on fetal sex, which may be due to sexually dimorphic epigenetic regulation of RNA expression. We identified sexually dimorphic miRNA expression throughout gestation in human placentae. Next-generation sequencing identified miRNA expression profiles in first and third trimester uncomplicated pregnancies using tissue obtained at chorionic villous sampling (n = 113) and parturition (n = 47). Sequencing analysis identified 986 expressed mature miRNAs from female and male placentae at first and third trimester (baseMean>10). Of these, 11 sexually dimorphic (FDR < 0.05) miRNAs were identified in the first and 4 in the third trimester, all upregulated in females, including miR-361-5p, significant in both trimesters. Sex-specific analyses across gestation identified 677 differentially expressed (DE) miRNAs at FDR < 0.05 and baseMean>10, with 508 DE miRNAs in common between female-specific and male-specific analysis (269 upregulated in first trimester, 239 upregulated in third trimester). Of those, miR-4483 had the highest fold changes across gestation. There were 62.5% more female exclusive differences with fold change>2 across gestation than male exclusive (52 miRNAs vs 32 miRNAs), indicating miRNA expression across human gestation is sexually dimorphic. Pathway enrichment analysis identified significant pathways that were differentially regulated in first and third trimester as well as across gestation. This work provides the normative sex dimorphic miRNA atlas in first and third trimester, as well as the sex-independent and sex-specific placenta miRNA atlas across gestation, which may be used to identify biomarkers of placental function and direct functional studies investigating placental sex differences.

Gender-Specific Response in Pain and Function to Biologic Treatment of Knee Osteoarthritis: A Gender-Bias-Mitigated, Observational, Intention-to-Treat Study at Two Years

Knee osteoarthritis is a major cause of disability worldwide. Newer modalities of treatment with less morbidity, such as intra-articular injection of microfragmented fat (MFAT), are showing promise. We report on our novel observation that women show a greater improvement in pain and function to MFAT than men. Traditionally, women have been underrepresented in studies and studies with both sexes regularly fail to analyze the results by sex. To mitigate for this bias and quantify it, we describe a technique using reproducible statistical analysis and replicable results with Open Access statistical software R to calculate the magnitude of this difference. Genetic, hormonal, environmental, and age factors play a role in our observed difference between the sexes. There is a need for further studies to identify the molecular basis for this difference and be able to utilize it to improve outcome for both women and men.

The sex ratio at birth - Historical aspects

This paper reviews the classical theories that attempted to explain the influences on the sex ratio at birth (M/F). These included notions pertaining to the four elements (earth, air, fire and water) and to laterality i.e. from which side of the body (in both parents) the conceptual principle arose. This narrative will also outline the initial physical measurements of male and female births and speculations by John Graunt (1620-1674), John Arbuthnott (1667-1735) and Johann Süssmilch (1707-1767), as well as the conundrums that M/F presented to Charles Darwin (1809-1882) and the theories of Ronald Fisher (1890-1962) who expanded on concepts first promulgated by Nicolas de Caritat, Marquis de Condorcet (1743-1794). Fortunately, the thousands of papers generated on topic, especially the more recent work pertaining to direct and measurable influences (such as exogenous stress periconceptually and during pregnancy) have begun to yield some concrete findings, indeed, "among this welter of evidence, it is possible to pin down a few facts" such that "we have found ourselves following Ariadne's thread to a series of clues that bind the calculation of the proportion of boys and girls at birth".

Does fetal sex affect placental delivery times? A prospective observational study

Objective: The aim of this study was to determine the potential effect of fetal sex on placental delivery times.Study design: This was a prospective observational study of term, singleton, and primiparous pregnant women who underwent vaginal delivery and subsequently delivered a phenotypically normal live infant. Women with labor or pregnancy complications and comorbid diseases were excluded. Women with factors who could lengthen the placental delivery time were also excluded. The cohort was divided into two groups according to fetal sex. A total of 299 vaginal deliveries were included, and placental delivery times were analyzed in both groups.Results: There were 3938 vaginal deliveries during the study period. Of these, 150 male-bearing pregnant women and 149 female-bearing pregnant women who met the inclusion criteria were included in the analysis. The mean placental delivery time was significantly longer in the male-bearing group than the female-bearing group (12.20 versus 8.21 min, p = .01). Birth weight was significantly greater in the male-bearing group than the female-bearing group (3194 versus 3059 g, p = .004). There was no significant between-group difference in maternal age, gestational age, and preconception body mass index (BMI).Conclusion: Fetal sex had a significant effect on the placental delivery time in the present study. Fetal sex should be considered in future clinical trials of placental delivery times.

Fetal sex influences maternal fasting plasma glucose levels and basal β-cell function in pregnant women with normal glucose tolerance

AIMS

Fetal sex has recently emerged as a new factor that is related to maternal glucose homeostasis during pregnancy. The present study aimed to investigate the effect of fetal sex on maternal glucose metabolism in women with normal glucose tolerance (NGT) during pregnancy in the Chinese population.

METHODS

A total of 877 pregnant women with NGT were recruited at 24-28 weeks of gestation and underwent a 75-g oral glucose tolerance test (OGTT). Pregnant women were divided into two groups according to fetal sex. Physical examinations and laboratory tests were performed. Pancreatic β-cell function and insulin sensitivity were evaluated using OGTT-derived indices.

RESULTS

Compared with women bearing female fetuses, women who delivered male fetuses had higher fasting plasma glucose (FPG) concentrations [4.5 (4.2-4.8) vs. 4.4 (4.2-4.7) mmol/L, P < 0.05], but lower HOMA-β [161.9 (118.2-238.8) vs. 181.0 (131.7-260.9), P < 0.05] and Stumvoll first phase of insulin secretion [1230.2 (1077.9-1433.7) vs. 1290.9 (1134.0-1493.2), P < 0.05]. Multiple linear regression analysis indicated that the sex of the fetus was independently associated with maternal FPG and HOMA-β. Further binary logistic regression analyses revealed that the presence of a male fetus was significantly associated with elevated FPG [odds ratio (OR) 1.50; 95% confidence interval (CI) 1.12-2.00; P = 0.006] and lower HOMA-β (OR 0.70; 95% CI 0.52-0.94; P = 0.018) even after adjustment for potential confounders.

CONCLUSIONS

This study provided evidence that maternal glucose metabolism could be affected by fetal sex even in NGT pregnant women. Our results suggest that the presence of male fetuses was independently associated with maternal elevated FPG and lower basal β-cell function.

The Association between Sex and Long-Term Pediatric Cardiovascular Morbidity

OBJECTIVE

To evaluate the association between sex and long-term pediatric cardiovascular morbidity.

STUDY DESIGN

A population-based cohort study was performed that compared the risk of long-term cardiovascular morbidity (up to the age of 18 years) of children according to sex. Deliveries occurred between the years 1991 and 2013 in a tertiary medical center. Multiple pregnancies and fetal congenital malformations were excluded. Kaplan-Meier survival curves were constructed to compare cumulative cardiovascular morbidity incidence. A Cox proportional hazards model was used to control for confounders, including gestational age at birth, birth weight, and maternal factors.

RESULTS

During the study period, 240 953 newborns met the inclusion criteria and were included in the long-term analysis. Of them, 51.0% (n = 122 840) were male and 49.0% (n = 118 113) female. Cardiovascular morbidity up to the age of 18 years was significantly more common in male as compared with female newborns (0.3% vs 0.2%, OR 1.33, 95% CI 1.12-1.57, P = .001). In the Cox regression model, male sex exhibited an independent association with long-term cardiovascular morbidity with an adjusted hazard ratio of 1.37 (95% CI 1.16-1.63, P <.001).

CONCLUSION

Male newborns are at an increased risk for pediatric cardiovascular morbidity independent of gestational age at birth and birth weight.

Effect of fetal gender on induction of labor failure rates

PURPOSE

To evaluate gender effect on induction of labor (IoL) failure rates stratified by indication to delivery.

METHODS

Retrospective cohort analysis of singleton pregnancies 34-42 weeks undergoing cervical ripening using controlled-release PGE2 vaginal insert. IoL Indications were divided into: (1) maternal; (2) hypertensive disorders; (3) premature rupture of membrane or (4) fetal (growth abnormalities, oligohydramnios, postdate, etc,). IoL failure was defined as: (1) Bishop-score ≤7 after 24 hours of PGE2; (2) cesarean delivery due to failed induction; (3) fetal distress followed by PGE2 removal and emergent cesarean. IoL failure rates were stratified by neonatal gender and indication to induction. Logistic regression analysis was utilized to control outcomes to potential confounders.

RESULTS

Overall, 1062 pregnancies were included - 521 (49%) had male fetuses. IoL indications did not differ by gender. IoL failure rate was 20.1% (213/1062) - 76% for unfavorable Bishop-score after PGE2 removal; 5.2% for failed induction and 18.8% for fetal-distress while on PGE2. Overall, 14.3% delivered by cesarean section. There were no differences in IoL failure as a group or by indications to induction stratified by fetal gender (21.7% vs. 18.5%, male vs. females, p < 0.05).

CONCLUSIONS

IoL failure rate is not affected by fetal gender regardless of indication to induction.

Can One Predict Resolution of Neonatal Hyperthyrotropinemia?

OBJECTIVE

To identify predictors of transience vs permanence of neonatal hyperthyrotropinemia. We hypothesized that infants with greater severity of perinatal stress are more likely to have transient thyrotropin elevations.

STUDY DESIGN

We retrospectively studied infants diagnosed with hyperthyrotropinemia between 2002 and 2014, following them for up to 12 years after diagnosis. Patients were divided into 3 groups: transient hyperthyrotropinemia (treatment was never prescribed), transient congenital hypothyroidism (treatment started but discontinued), and permanent congenital hypothyroidism (withdrawal unsuccessful or not attempted). We performed univariate and multiple logistic regression analyses, including and excluding infants with maternal thyroid disease.

RESULTS

We included 76 infants, gestational age mean (±SD) 34.2 (±5.7) weeks, evaluated for hyperthyrotropinemia. Thirty-five (46%) were never treated, and 41 (54%) received levothyroxine. Of the treated patients, 16 successfully discontinued levothyroxine, and for 25 withdrawal either failed or was not attempted. We found that male patients were almost 5 times more likely than female patients to have transient neonatal hyperthyrotropinemia (OR 4.85; 95% CI 1.53-15.37). We documented greater maternal age (31.5 ± 5.48 years vs 26 ± 6.76 years, mean ± SD, P = .02), greater rate of cesarean delivery (86.7% vs 54.2%; P = .036), and retinopathy of prematurity (37.5% vs 8%; P = .02) in the group with transient congenital hypothyroidism vs the group with permanent congenital hypothyroidism.

CONCLUSION

The results show transience of neonatal thyrotropin elevations in a majority of patients and suggest a possible association of hyperthyrotropinemia with maternal and perinatal risk factors.

Exposure to pistachio pesticides and stillbirth: a case-control study

OBJECTIVES

Stillbirth is an undesirable outcome of pregnancy. In light of the increasing use of pesticides and growing concerns about the possible health effects of agricultural pesticides, we investigated the effect of exposure to pistachio pesticides on stillbirth in pregnant mothers.

METHODS

This case-control study was conducted in Rafsanjan, Iran from 2011 to 2012. A total of 125 females who had a recent stillbirth were included as the case group, and 250 controls were selected from females who had a recent live birth. For each case, two controls with the nearest propensity score to the case were selected. Data were collected using a protocol developed by the researcher that involved interviewing respondents and reviewing their medical records. Conditional multivariate and univariate logistic regression analysis were performed and odds ratios (ORs) and 95% confidence intervals (CIs) were calculated.

RESULTS

The ORs of stillbirth in mothers living in pistachio gardens and those who were exposed to sprayed pesticides, in comparison to the controls, were 14.1 (95% CI, 3.3 to 63.4) and 5.0 (95% CI, 1.2 to 28.6), respectively. No significant differences were found in stillbirth rates according to the distance between the mother's residence and a pistachio garden or involvement in agricultural activities.

CONCLUSIONS

The results of our study showed that exposure to pistachio pesticides during pregnancy may increase the likelihood of stillbirth in mothers.

Neonatal outcomes in relation to sex differences: a national cohort survey in Taiwan

Background

An extensive assessment investigating the association between sex differences and neonatal outcomes is lacking. In the current study, we estimated the correlation of gender with adverse birth outcomes in a large cohort population.

Methods

National population-based data containing maternal and neonatal information in 2001 to 2010 were derived from the Health Promotion Administration, Taiwan. Singletons without high-risk pregnancy were further analyzed for the sex ratio of live births in relation to neonatal outcomes—including preterm birth, birth weight, neonatal death, delivery mode, and congenital anomaly. A multivariate logistic regression model was used to adjust for possible confounders.

Results

In total, 2,123,100 births were valid for the analysis. Overall, the sex ratio at birth (male/female) was 1.096. Compared to multiple births, the sex ratio was significantly higher with singleton births (p < 0.001). Among multiple births, the incidence of stillbirths was significantly higher in males than in females (p < 0.05). The sex ratio at gestational age (GA) <37 weeks was 1.332, and it declined proportionally with a rise in the GA to 0.899 at GA of ≥41 weeks. In contrast, the sex ratio was 0.850 at birth weight <3000 g, and it rose proportionally with a rise in the birth weight to 1.902 at birth weight ≥4000 g (macrosomia). Operative delivery was more common in males than in females (p < 0.001). The regression analysis showed greater risks of preterm birth, macrosomia, operative delivery, neonatal death, and congenital anomaly among male newborns.

Conclusions

Male gender carried higher risks of adverse neonatal outcomes, including preterm birth, macrosomia, operative delivery, neonatal death, and congenital anomaly. The data have clinical implications on health surveillance for plotting strategies in response to the unbalanced sex ratio in relation to the boy preference.

Combined effect of fetal sex and advanced maternal age on pregnancy outcomes

BACKGROUND

Fetal sex and maternal age are each known to affect outcomes of pregnancies. The objective of the present study was to investigate the influence of the combination of maternal age and fetal sex on pregnancy outcomes in term and post-term singleton pregnancies.

MATERIAL AND METHODS

This was a retrospective study on term singleton pregnancies delivered between 2004 and 2008 at the Chaim Sheba Medical Center. Data collected included maternal age, fetal sex, and maternal and neonatal complications. The combined effect of fetal sex and maternal age on complications of pregnancy was assessed by multivariable logistic regression models.

RESULTS

The study population comprised 37,327 pregnancies. The risk of operative deliveries increased with maternal age ≥ 40 and in pregnancies with male fetuses. The risk of maternal diabetes and of longer hospitalization increased as maternal age increased, and in women ≥ 40 carrying male fetuses. The risk of hypertensive disorders increased in pregnancies with males as maternal age advanced. The risk of shoulder dystocia and neonatal respiratory complications increased in male neonates born to women<40. The risk of neonatal hypoglycemia increased in males for all maternal ages.

CONCLUSIONS

Risk assessment for fetal sex and advanced maternal age were given for different pregnancy complications. Knowledge of fetal sex adds value to the risk assessment of pregnancies as maternal age increases.

Cross sectional study in China: fetal gender has adverse perinatal outcomes in mainland China

Background

The association between fetal gender and pregnancy outcomes has been thoroughly demonstrated in western populations. However, this association has not been thoroughly documented in China. The primary objective of the present study is to determine whether the association of adverse pregnancy and labour outcomes with male fetuses applies to the Chinese population.

Methods

This cross-sectional hospital-based retrospective survey collected data from thirty-nine hospitals in 2011 in mainland China. A total of 109,722 women with singleton pregnancy who delivered after 28 weeks of gestation were included.

Results

Of these pregnancies, the male-to-female sex ratio was 1.2. The rates of preterm birth (7.3% for males, 6.5% for females) and fetal macrosomia (8.3% for males, 5.1% for females) were higher for male newborns, whereas fetal growth restriction (8.0% for females, 5.4% for males) and malpresentation (4.3% for females, 3.6% for males) were more frequent among female-bearing mothers. A male fetus was associated with an increased incidence of operative vaginal delivery (1.3% for males, 1.1% for females), caesarean delivery (55.0% for males, 52.9% for females), and cephalopelvic disproportion/failure to progress (10.0% for males, 9.2% for female). Male gender was also significantly associated with lower Apgar scores (<7 at 5 min, adjusted odds ratio 1.3, 95% CI 1.0-1.6), as well as a neonatal intensive care unit admission and neonatal death, even after adjustments for confounders (adjusted odds ratio 1.3, 95% CI 1.1-1.5, adjusted odds ratio 1.4, 95% CI 1.1-1.8).

Conclusion

We confirm the existence of obvious neonatal gender bias and adverse outcomes for male fetuses during pregnancy and labour in our population. Further research is required to understand the mechanisms and clinical implications of this phenomenon.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-014-0372-4) contains supplementary material, which is available to authorized users.

Fetal gender and pregnancy outcomes in Libya: a retrospective study

Objective

The relationship between pregnancy outcomes and fetal gender is well reported from different areas in the world, but not from Africa. In this study, we try to understand whether the recorded phenomenon of association of adverse pregnancy outcomes with a male fetus applies to our population.

Materials and methods

A total of 29,140 patient records from 2009 and 2010 were retrieved from Aljalaa Maternity Hospital, Tripoli, Libya. Analysis was carried out to find the correlation between fetal gender and different pregnancy outcomes.

Results

A male fetus was associated with an increased incidence of gestational diabetes mellitus (odds risk 1.4), preterm delivery (6.7% for males, 5.5% for females, odds risk 1.24), cesarean section (23.9% for males, 20% for females, odds risk 1.25), and instrumental vaginal delivery (4.4% for males, 3.1% for females, odds risk 1.48), p<0.005. Preeclampsia was more frequent among preterm females and postterm males, p<0.005. It was also more frequent in male-bearing primigravids, p<0.01.

Conclusion

We confirm the existence of an adverse effect of a male fetus on pregnancy and labor in our population. We recommend further research to understand the mechanisms and clinical implications of this phenomenon.

Are male neonates more vulnerable to neonatal abstinence syndrome than female neonates?

BACKGROUND

Prior studies have shown an increased vulnerability among males to adverse outcomes during the postnatal period. Most children exposed to opioids and other medications in utero develop neonatal abstinence syndrome (NAS), yet individual predisposition for NAS is poorly understood.

OBJECTIVE

This investigation examined the role of neonatal sex in the postnatal period for neonates exposed to standardized opioid maintenance treatment in utero with a focus on NAS regarding severity, medication requirements, and duration.

METHODS

This was a secondary analysis of data collected in a prospective randomized, double-blind, double-dummy, multicenter trial (MOTHER study) that examined the comparative safety and efficacy of methadone and buprenorphine during pregnancy. A total of 131 neonates born to opioid-dependent women randomized at 6 US sites (n = 74) and 1 European site (n = 37) were analyzed. Sex-based differences in birth weight, length, head circumference, NAS duration, NAS severity, and treatment parameters of full-term neonates were assessed.

RESULTS

Males had a significantly higher birth weight (P = 0.027) and head circumference (P = 0.017) compared with females, with no significant sex difference in rates of preterm delivery. No significant sex-related differences were found for NAS development, severity, or duration, or medication administered, and there were no significant differences in concomitant drug consumption during pregnancy (P = 0.959).

CONCLUSIONS

This unique prospective study shows similar postnatal vulnerability for both sexes, suggesting that factors other than sex are the major determinants of clinically significant NAS. ClinicalTrials.gov identifier: NCT 00271219.