Prepregnancy Body Mass Index and Infant Mortality in 38 U.S. States, 2012-2013

Non-linear associations of maternal pre-pregnancy body mass index with risk of stillbirth, infant, and neonatal mortality in over 28 million births in the USA: a retrospective cohort study

Background

Higher maternal pre-pregnancy body mass index (BMI) has been associated with higher risk of stillbirth, infant and neonatal mortality. Studies exploring underweight have varied in their conclusions. Our aim was to examine the risk of stillbirth, infant and neonatal mortality across the BMI distribution and establish a likely healthy BMI range.

Methods

In this retrospective cohort study, we used publicly available datasets (covering 1st January 2014 to 31st December 2021) from the US National Center for Health Statistics National Vital Statistics System. All births were eligible; analyses included those with non-missing data. Fractional polynomial multivariable logistic regression was used to examine the associations of maternal pre-pregnant BMI with stillbirth (birth with no signs of life at ≥24 weeks), infant mortality (death of a live born baby aged <365 days) and neonatal mortality (death of a live born baby aged <28 days).

Findings

There were 77,896/28,310,154 (2.8 per 1000 births) stillbirths, 143,620/28,231,807 (5.1 per 1000 live births) infant deaths and 94,246/28,231,807 (3.3 per 1000 live births) neonatal deaths among complete cases. Mean (SD) BMI was 27.1 kg/m2 (6.7 kg/m2). We found non-linear associations between BMI and all three outcomes; risk was elevated at both low and high BMIs although, for stillbirth, the increased risk at low BMI was less marked than for infant/neonatal mortality. The lowest risk was at a BMI of 21 kg/m2 for infant and neonatal mortality and 19 kg/m2 for stillbirth.

Interpretation

Public health messaging for preconception and postnatal care should focus on healthy weight to maximise maternal and child health, and not focus solely on maternal overweight or obesity.

Funding

European Research Council, US National Institute of Health, UK Medical Research Council and National Institute for Health and Care Research.

Disparities in infant mortality by maternal race and Hispanic origin, 2017-2018

Disparities in infant mortality by race and Hispanic origin groups continue to persist in the United States. Maternal and infant characteristics known to be associated with infant mortality vary by race and ethnicity. This report describes racial and ethnic disparities in infant mortality in the United States using the 2017-2018 cohort linked birth/infant death files from the National Vital Statistics System. Distributions of births and infant mortality rates are described by selected maternal and infant characteristics. Adjusted rates and rate ratios from logistic regression models, compared to unadjusted rates and ratios, show the extent to which race and Hispanic origin disparities would be attenuated if all groups had the same distributions of select maternal and infant factors. Results support the premise that the different distributions of several variables across racial/ethnic groups, most notably gestational age, account for a significant portion of the disparities in infant mortality between racial/ethnic groups.

Early Antibiotic Exposure and Adverse Outcomes in Very Preterm Infants at Low Risk of Early-Onset Sepsis: The EPIPAGE-2 Cohort Study

OBJECTIVE

To assess the association between early empirical antibiotics and neonatal adverse outcomes in very preterm infants without risk factors for early-onset sepsis (EOS).

STUDY DESIGN

This is a secondary analysis of the EPIPAGE-2 study, a prospective national population-based cohort that included all liveborn infants at 22-31 completed weeks of gestation in France in 2011. Infants at high risk of EOS (ie, born after preterm labor or preterm premature rupture of membranes or from a mother who had clinical chorioamnionitis or had received antibiotics during the last 72 hours) were excluded. Early antibiotic exposure was defined as antibiotic therapy started at day 0 or day 1 of life, irrespective of the duration and type of antibiotics. We compared treated and untreated patients using inverse probability of treatment weighting based on estimated propensity scores.

RESULTS

Among 648 very preterm infants at low risk of EOS, 173 (26.2%) had received early antibiotic treatment. Early antibiotic exposure was not associated with death or late-onset sepsis or necrotizing enterocolitis (OR, 1.04; 95% CI, 0.72-1.50); however, it was associated with higher odds of severe cerebral lesions (OR, 2.71; 95% CI, 1.25-5.86) and moderate-severe bronchopulmonary dysplasia (BPD) (OR, 2.30; 95% CI, 1.21-4.38).

CONCLUSIONS

Early empirical antibiotic therapy administrated in very preterm infants at low risk of EOS was associated with a higher risk of severe cerebral lesions and moderate-severe BPD.

Prevalence and Social and Built Environmental Determinants of Maternal Prepregnancy Obesity in 68 Major Metropolitan Cities of the United States, 2013-2016

Objective

Maternal prepregnancy obesity is related to increased maternal morbidity and mortality and poor birth outcomes. However, prevalence and risk factors for prepregnancy obesity in US cities are not known. This study examines the prevalence and social and environmental determinants of maternal prepregnancy obesity (BMI ≥30), overweight/obesity (BMI ≥25), and severe obesity (BMI ≥40) in the 68 largest metropolitan cities of the United States.

Methods

We fitted logistic and Poisson regression models to the 2013–2016 national vital statistics birth cohort data (N = 3,083,600) to derive unadjusted and adjusted city differentials in maternal obesity and to determine social and environmental determinants.

Results

Considerable disparities existed across cities, with the prevalence of prepregnancy obesity ranging from 10.4% in San Francisco to 36.6% in Detroit. Approximately 63.0% of mothers in Detroit were overweight or obese before pregnancy, compared with 29.2% of mothers in San Francisco. Severe obesity ranged from 1.4% in San Francisco to 8.5% in Cleveland. Women in Anchorage, Buffalo, Cleveland, Fresno, Indianapolis, Louisville, Milwaukee, Oklahoma City, Sacramento, St Paul, Toledo, Tulsa, and Wichita had >2 times higher adjusted odds of prepregnancy obesity compared to those in San Francisco. Race/ethnicity, maternal age, parity, marital status, nativity/immigrant status, and maternal education were important individual-level risk factors and accounted for 63%, 39%, and 72% of the city disparities in prepregnancy obesity, overweight/obesity, and severe obesity, respectively. Area deprivation, violent crime rates, physical inactivity rates, public transport use, and access to parkland and green spaces remained significant predictors of prepregnancy obesity even after controlling for individual-level covariates.

Conclusions

Substantial disparities in maternal prepregnancy obesity among the major US cities remain despite risk-factor adjustment, with women in several Southern and Midwestern cities experiencing high risks of obesity. Sound urban policies are needed to promote healthier lifestyles and favorable social and built environments for obesity reduction and improved maternal health.

Cause of preterm birth and late-onset sepsis in very preterm infants: the EPIPAGE-2 cohort study

BACKGROUND

The pathogenesis of late-onset sepsis (LOS) in preterm infants is poorly understood and knowledge about risk factors, especially prenatal risk factors, is limited. This study aimed to assess the association between the cause of preterm birth and LOS in very preterm infants.

METHODS

2052 very preterm singletons from a national population-based cohort study alive at 72 h of life were included. Survival without LOS was compared by cause of preterm birth using survival analysis and Cox regression models.

RESULTS

437 (20.1%) had at least one episode of LOS. The frequency of LOS varied by cause of preterm birth: 17.1% for infants born after preterm labor, 17.9% after preterm premature rupture of membranes, 20.3% after a placental abruption, 20.3% after isolated hypertensive disorders, 27.5% after hypertensive disorders with fetal growth restriction (FGR), and 29.4% after isolated FGR. In multivariate analysis, when compared to infants born after preterm labor, the risk remained higher for infants born after hypertensive disorders (hazard ratio HR = 1.7, 95% CI = 1.2-2.5), hypertensive disorders with FGR (HR = 2.6, 95% CI = 1.9-3.6) and isolated FGR (HR = 2.9, 95% CI = 1.9-4.4).

CONCLUSION

Very preterm infants born after hypertensive disorders or born after FGR had an increased risk of LOS compared to those born after preterm labor.

IMPACT

Late-onset sepsis risk differs according to the cause of preterm birth. Compared with those born after preterm labor, infants born very preterm because of hypertensive disorders of pregnancy and/or fetal growth restriction display an increased risk for late-onset sepsis. Antenatal factors, in particular the full spectrum of causes leading to preterm birth, should be taken into consideration to better prevent and manage neonatal infectious morbidity and inform the parents.

Association of Maternal Body Mass Index With Risk of Infant Mortality: A Dose-Response Meta-Analysis

Objective: This study presumed that a high or low body mass index (BMI) might increase the risk of infant mortality. Therefore, a meta-analysis was performed to systematically assess the association between maternal BMI and the risk of infant mortality. Methods: The electronic databases, including Pubmed, Embase database, and Cochrane Library, were systemically searched by two investigators from inception to November 26th, 2020, with no language restriction. In parallel, a dose-response was assessed. Results: Finally, 22 cohort studies involving 13,532,293 participants were included into this paper, which showed that compared with normal BMI, maternal overweight significantly increased the risks of infant mortality [risk ratio (RR), 1.16; 95% confidence interval (CI), 1.13-1.19], neonatal mortality (RR, 1.23; 95% CI, 1.08-1.39), early neonatal mortality (RR, 1.55; 95% CI, 1.26-1.92) and post-neonatal mortality (RR, 1.18; 95% CI, 1.07-1.29). Similarly, maternal obesity significantly increased the risk of infant mortality (RR, 1.55; 95% CI, 1.41-1.70), neonatal mortality (RR, 1.55; 95% CI, 1.28-1.67), early neonatal mortality (RR, 1.37; 95% CI, 1.13-1.67), and post-neonatal mortality (RR, 1.30; 95% CI, 1.03-1.65), whereas maternal underweight potentially decreased the risk of infant mortality (RR, 0.93; 95% CI, 0.88-0.98). In the dose-response analysis, the risk of infant mortality significantly increased when the maternal BMI was >25 kg/m². Conclusions: Maternal overweight or obesity significantly increases the risks of infant mortality, neonatal mortality, early neonatal mortality, and post-neonatal mortality compared with normal BMI in a dose-dependent manner. Besides, maternal underweight will not increase the risk of infant mortality, neonatal mortality, early neonatal mortality, or postneonatal mortality; instead, it tends to decrease the risk of infant mortality. Early weight management may provide potential benefits to infants, and more large-scale prospective studies are needed to verify this finding in the future.

Geographic Variation in Sudden Unexpected Infant Death in the United States

OBJECTIVES

To assess the geographic variation of sudden unexpected infant death (SUID) and test if variation in geographic factors, such as state, latitude, and longitude, play a role in SUID risk across the US.

STUDY DESIGN

We analyzed the Centers for Disease Control and Prevention's Cohort Linked Birth/Infant Death dataset (2005-2010; 22 882 SUID cases, 25 305 837 live births, rate 0.90/1000). SUID was defined as infant deaths (ages 7-364 days) that included sudden infant death syndrome, ill-defined and unknown cause of mortality, and accidental suffocation and strangulation in bed. SUID geographic variation was analyzed using 2 statistical models, logistic regression and generalized additive model (GAM).

RESULTS

Both models produced similar results. Without adjustment, there was marked geographic variation in SUID rates, but the variation decreased after adjusting for covariates including known risk factors for SUID. After adjustment, nine states demonstrated significantly higher or lower SUID mortality than the national average. Geographic contribution to SUID risk in terms of latitude and longitude were also attenuated after adjustment for covariates.

CONCLUSION

Understanding why some states have lower SUID rates may enhance SUID prevention strategies.

Neonatal and neurodevelopmental outcomes in preterm infants according to maternal body mass index: A prospective cohort study

OBJECTIVE

Maternal obesity is associated with an increase in maternal, foetal and neonatal morbidity and mortality. The aim of our study was to evaluate the relationships between maternal pre-pregnancy body mass index and (1) neonatal outcome in preterm infants, and (2) neurodevelopmental outcome at 2 years of corrected age.

METHOD

We conducted a single-centre cohort study. Infants born between 24+0 and 33+6 weeks of gestation between January 2009 and December 2013, hospitalised in the neonatal intensive care unit of Angers University Hospital, and with available data regarding maternal pre-pregnancy body mass index were eligible. Three groups were defined according to maternal body mass index: normal (n = 418), overweight (n = 136) and obese (n = 89). The primary outcome was neurodevelopment at 2 years of corrected age. Children with a non-optimal neuromotor and/or psychomotor assessment and/or a sensory disability were regarded as having a "non-optimal neurodevelopmental outcome". Neuromotor function was regarded as non-optimal when cerebral palsy was present or when the clinical examination revealed neurological signs of abnormal muscular tone. Psychomotor assessment was regarded as non-optimal if the revised Brunet-Lézine test was < 85 or when the overall score in the parental Ages and Stages Questionnaire (ASQ) was < 185. Finally, sensory disabilities such as blindness and children who required a hearing aid were taken into account. The secondary outcome was the composite criteria of neonatal complications. Multivariable analysis included the following variables: mother's age, gestational age, smoking during pregnancy, magnesium sulphate and steroid treatment during pregnancy, twin status, gender, socioeconomic status and social security benefits for those with low incomes.

RESULTS

The study population was composed of 643 preterm infants. Among them, 520 were assessed at 2 years. There was no difference in the proportion of infants with non-optimal neurodevelopmental outcomes between the three groups (16.6% for obese, 13.5% for overweight, 16.9% for normal body mass index mothers; p = 0.73). According to multivariable analysis, being born from an overweight or obese mother was not associated with an increased risk of non-optimal neuro-development at 2 years (adjusted OR = 0.84 [0.40-1.76] for obese, adjusted OR = 0.83 [0.43-1.59] for overweight mothers). There was no difference in the proportion of preterm infants with a non-optimal composite criterion of neonatal complications between the three groups. In the multivariable analysis, being born from an overweight or obese mother was not associated with an increased risk of non-optimal neonatal outcomes (adjusted OR = 0.95 [0.49-1.83] for obese, adjusted OR = 1.18 [0.69-2.01] for overweight mothers).

CONCLUSION

In this large prospective cohort of preterm infants born before 34 weeks of gestation, we found no relationship between maternal body mass index and neurodevelopmental outcomes at 2 years of corrected age and no relationship between maternal body mass index and neonatal outcomes. Other prematurity-related factors may be more relevant for neurodevelopmental outcome than the mother's pre-pregnancy BMI.

Survival of infants with spina bifida and the role of maternal prepregnancy body mass index

OBJECTIVE

To investigate first-year survival of infants born with spina bifida, and examine the association of maternal prepregnancy body mass index (BMI) with infant mortality.

METHODS

This is a retrospective cohort study of 1,533 liveborn infants with nonsyndromic spina bifida with estimated dates of delivery from 1998 to 2011 whose mothers were eligible for the National Birth Defects Prevention Study (NBDPS). NBDPS data were linked to death records to conduct survival analyses. Kaplan-Meier survival functions estimated mortality risk over the first year of life. Cox proportional hazards models estimated hazard ratios (HRs) for maternal prepregnancy BMI categorized as underweight (<18.5), normal (18.5-24.9), overweight (25-29.9), and obese (≥30).

RESULTS

Infant mortality risk among infants with spina bifida was (4.4% [3.52, 5.60%]). Infants with multiple co-occurring defects, very preterm delivery, multiple gestation, high-level spina bifida lesions, or non-Hispanic Black mothers had an elevated risk of infant mortality. Maternal prepregnancy underweight and obesity were associated with higher infant mortality (15.7% [7.20, 32.30%] and 5.82% [3.60, 9.35%], respectively). Adjusted HR estimates showed underweight and obese mothers had greater hazard of infant mortality compared to normal weight mothers (HR: 4.5 [1.08, 16.72] and 2.6 [1.36, 8.02], respectively).

CONCLUSION

The overall risk of infant mortality for infants born with spina bifida was lower than most previously reported estimates. Infants born with spina bifida to mothers who were underweight or obese prepregnancy were at higher risk of infant mortality. This study provides additional evidence of the importance of healthy maternal weight prior to pregnancy.

Maternal Undernutrition and Breast Milk Macronutrient Content Are Not Associated with Weight in Breastfed Infants at 1 and 3 Months after Delivery

This study examined whether maternal nutritional intake and breast milk macronutrient content influence the weight of breastfed infants. We investigated 129 healthy mothers with singleton babies born from July 2016 to December 2017 in a university hospital in Tokyo, Japan. Information was obtained by a self-administered food frequency questionnaire at 1 (valid response n = 92; mean age, 34 years) and 3 (n = 57) months after delivery. Breast milk was sampled at 1 and 3 months and the macronutrient contents were analyzed. The average pre-pregnancy body mass index and weight gain during pregnancy were 20.7 ± 2.6 kg/m² and 9.6 ± 3.7 kg, respectively. At 1 month, average maternal calorie intake was 1993 ± 417 kcal/day, which was lower than the intake recommended by Japanese Dietary Reference Intakes for breastfeeding mothers. There were no significant differences with regard to maternal calorie and protein intake, and breast milk macronutrient content between breastfed infants with weight above and below the 25th percentile of its distribution at both 1 and 3 months. This study suggests that suboptimal calorie intake by breastfeeding mothers and breast milk macronutrient content were not associated with weight of their infants at 1 and 3 months after delivery.

Marked Disparities in Pre-Pregnancy Obesity and Overweight Prevalence among US Women by Race/Ethnicity, Nativity/Immigrant Status, and Sociodemographic Characteristics, 2012-2014

This study examines racial/ethnic, nativity, and sociodemographic disparities in the prevalence of pre-pregnancy obesity and overweight in the United States. Logistic regression was fitted to the 2012-2014 national birth cohort data to derive unadjusted and adjusted differentials in pre-pregnancy obesity (BMI ≥30), severe obesity (BMI ≥40), and overweight/obesity (BMI ≥25) prevalence among 10.4 million US women of childbearing age. Substantial racial/ethnic differences existed, with pre-pregnancy obesity rates ranging from 2.6% for Chinese and 3.3% for Vietnamese women to 34.9% for American Indians/Alaska Natives (AIANs) and 60.2% for Samoans. Pre-pregnancy overweight/obese prevalence ranged from 13.6% for Chinese women to 61.7% for AIANs and 86.3% for Samoans. Compared to non-Hispanic whites, women in all Asian subgroups had markedly lower risks of pre-pregnancy obesity, severe obesity, and overweight/obesity, whereas Samoans, Hawaiians, AIANs, blacks, Mexicans, Puerto Ricans, and Central/South Americans had significantly higher risks. Immigrant women in each racial/ethnic group had lower rates of pre-pregnancy obesity than the US-born. Sociodemographic risk factors accounted for 33-47% of racial/ethnic disparities and 12-16% of ethnic-immigrant disparities in pre-pregnancy obesity and overweight/obesity. Further research is needed to assess the effects of diet, physical inactivity, and social environments in explaining the reported ethnic and nativity differences in pre-pregnancy obesity.

Obstetric and perinatal outcomes in subfertile patients who conceived following low technology interventions for fertility enhancement: a comprehensive review

PURPOSE

Low technology interventions for fertility enhancement (LTIFE) are strategies that avoid retrieval, handling, and manipulation of female gametes. The definition of LTIFE is yet to be widely accepted and clarified, but they are commonly used in milder cases of infertility and subfertility. Based on these considerations, the aim of the present study was comprehensively to review and investigate the obstetric and perinatal outcomes in subfertile patients who underwent LTIFE.

METHODS

A literature search up to May 2017 was performed in IBSS, SocINDEX, Institute for Scientific Information, PubMed, Web of Science, and Google Scholar. An evidence-based hierarchy was used according to The Oxford Centre for Evidence-Based Medicine to determine which articles to include and analyze, and to provide a level of evidence of each association between intervention and outcome.

RESULTS

This analysis identified preliminary and low-grade evidence on the influence of LTIFE on obstetric and perinatal outcomes in subfertile women.

CONCLUSIONS

LTIFE women should deserve major consideration from Clinicians/Researchers of Reproductive Medicine, because these treatments could be potentially responsible for mothers' and babies' complications. So far, the lack of well-designed and unbiased studies makes further conclusions difficult to be drawn.

Is maternal body mass index associated with neonatal mortality? A pooled analysis of nationally representative data from nine Asian countries

OBJECTIVE

Children born to mothers with abnormal body mass index (BMI) have increased risk for mortality. The aim of this study was to investigate whether maternal BMI is a risk factor for neonatal death in select Asian countries, including the nature of association between maternal BMI and the discrete timing of neonatal death.

METHODS

Nationally representative, the standard Demographic and Health Survey data from nine Asian countries were used. In all, 55 629 mothers reported their index birth; 840 reported neonatal mortality. Descriptive statistics and multivariate logistic regression analyses were applied to attain the study objective.

RESULTS

Overweight mothers had higher odds of neonatal mortality than mothers with optimum weight. No significant association was registered for obese mothers, possibly due to insufficient power. During the first 7 d (0-1 and 2-6 d) of birth, children born to overweight mothers had higher odds of dying, whereas for the remaining period (7-27 d), maternal underweight was the risk factor for neonatal mortality.

CONCLUSION

Interventions should target high-risk pregnancies to reduce the rate of neonatal mortality. With the help of community health workers or physicians, preconception counseling of prospective mothers with abnormal BMI should be devised. If conceived, underweight or overweight or obese women should be marked as high-risk pregnancy during their antenatal care visits, and they must be encouraged for delivery at an institution equipped with an emergency obstetric and neonatal care unit.

Gestational weight gain and the risk of infant mortality amongst women with normal prepregnancy BMI: the Friedmann-Balayla model

OBJECTIVE

The study of the association between gestational weight gain (GWG) and infant mortality is riddled with methodological concerns, particularly with limitations in accounting for gestational age-specific weight gain. In our study, we developed a new model, which accounts for gestational age, to determine whether insufficient or excessive GWG is associated with an increased risk of infant death amongst women with normal prepregnancy BMI (18.5-24.9 kg/m²).

METHODS

We developed and implemented the Friedmann-Balayla model to mitigate gestational age-related biases in our assessment, and conducted a population-based cohort study using the CDC's 2013 Period-Linked Birth-Infant Death data. The impact of GWG according to the 2009 IOM guidelines on the risk of infant mortality was estimated using logistic regression analysis, adjusting for relevant confounders.

RESULTS

Our cohort consisted of 1,517,525 singleton deliveries and 6138 infant deaths. Overall, relative to women achieving adequate GWG, neither women gaining insufficient nor excessive weight had greater odds of infant death during the first year of life (OR [95%CI]): 1.06 [0.97-1.17] (p = 0.174), and 0.98 [0.91-1.04] (p = 0.523), respectively. This relationship did not change when restricting our analysis to term or preterm deliveries or when conducting sensitivity analyses accounting for maternal morbidities (p > 0.05).

CONCLUSION

Using this novel analytic approach, there does not appear to be an increased risk of infant mortality if GWG falls outside of the IOM guidelines in women with normal prepregnancy BMI. Future studies should apply this methodology to other BMI categories.

Perspectives in obesity and pregnancy

Obesity is currently recognized as a health epidemic worldwide. Its prevalence has doubled in the last three decades. Obesity is a complex clinical picture associated with physical, physiologic, hormonal, genetic, cultural, socioeconomic and environmental factors. The rate of obesity is also increasing in the pregnant women population. Maternal obesity is associated with less than optimal obstetrical, fetal and neonatal outcomes. It is also associated with significant adverse long-term effects on both obese parturients and the infants born from obese women. A number of guidelines have been published to educate health care workers and the general population in an attempt to develop effective interventions on a large scale to prevent obesity. These guidelines are multiple, confusing and inconsistent. There are no standard recommendations regarding gestational weight gaining goals, nutrients and additional elements necessary for certain obese women who have been treated with bariatric surgical procedures, screening for metabolic diseases such as diabetes, additional preventive health care services indicated for obese women in the pregnancy planning stages, during prenatal care, in the immediate post-partum period and as a long-term approach for health preservation. In 2013, the American Medical Association supported by several US national medical specialty organizations published Resolution 420 (A-13) recognizing obesity as a disease state with multiple pathophysiological aspects requiring a range of interventions to improve its prevention and treatment. The goal of this decision was to encourage a broader spectrum of health care benefits insurance coverage for the prevention and treatment of obesity. There are a number of myths and misconceptions associated with obesity. These perspectives present our views and clinical experience with a partial review of recent bibliography addressing the associations between obese reproductive age women and their risks during pregnancy.

Pregnancy complications in spontaneous and assisted conceptions of women with infertility and subfertility factors. A comprehensive review

In the literature, there is growing evidence that assisted reproductive techniques increase the risk of pregnancy complications in subfertile couples. Moreover, many concomitant preconception risk factors for subfertility are frequently present in the same subject and increase the risk of pregnancy complications. This review aimed to summarize in a systematic fashion the best current evidence regarding the effects of preconception maternal factors on maternal and neonatal outcomes. A literature search up to March 2016 was performed in IBSS, SocINDEX, Institute for Scientific Information, PubMed, Web of Science and Google Scholar. An evidence-based hierarchy was used to determine which articles to include and analyse. Available data show that the risk of pregnancy complications in spontaneous and assisted conceptions is likely multifactorial, and the magnitude of this risk is probably very different according specific subgroups of patients. Notwithstanding the only moderate level and quality of the available evidence, available data suggest that the presence and the treatment of specific preconception cofactors of subfertility should be always taken into account both in clinical practice and for scientific purposes.