Small-for-gestational age and preterm birth across generations: a population-based study of Illinois births

Intergenerational Occurrence of Premature Birth and Reproductive Health in Prematurely-Born Women in the Women's Health Initiative

OBJECTIVE

To compare reproductive history and postmenopausal health by birth status (preterm vs. full term) in a U.S. longitudinal study of postmenopausal women. Birth status was examined according to region of residence, household, and neighborhood socioeconomic status (SES).

METHODS

In the Women's Health Initiative Observational Study, 2271 women were born prematurely (< 37 weeks). ANOVA and Chi-square determined birth status differences of reproductive history, pregnancy, and postmenopausal health. Odds ratios were calculated using either binary logistic or multinomial logistic regression. SES and U.S. region of residence were examined as potential effect modifiers.

RESULTS

Preterm-born women compared to term-born women had higher risk of delivering a premature infant (aOR 1.68, 95% CI [1.46, 1.93]), higher odds of later-age first pregnancy (aOR 1.27 95% CI [1.02, 1.58]), longer duration to become pregnant (> 1 year to pregnancy) (aOR 1.10 95% CI [1.01, 1.21]), more miscarriages (aOR 1.23 95% CI [1.11, 1.37]), and more pregnancy complications including hypertension (aOR 1.58 95% CI (1.13, 2.21)], preeclampsia (aOR 1.64 95% CI [1.24, 2.16]), and gestational diabetes (aOR 1.68 95% CI [1.11, 2.53]). Preterm-born women had higher odds of menopause before age 50 (aOR 1.09 95% CI [1.05, 1.14]). Post-menopause, they had higher rates of diabetes (p = .01), hypertension (p = .01), hysterectomy (p = .045), and higher Charlson Comorbidity Index scores (p = .01).

CONCLUSIONS

Preterm-born women had higher reproductive and pregnancy risks which when coupled with early menopause, may indicate a shorter childbearing period than term-born women. Guidelines for integration of preterm history in women's health care across the life course are needed to identify and manage their higher risk.

Preconception mitochondrial DNA copy number plays a crucial role in linking prenatal air pollution with the risk of preterm birth

The relationship between maternal peripheral blood mitochondrial DNA and adverse pregnancy outcomes, specifically preterm birth (PTB), remains uncertain. To investigate the effects of preconception mitochondrial DNA copy number (mtDNAcn) on the association between prenatal air pollutants exposure and PTB risk, a total of 1871 expectant mothers from six regions in Henan Province were recruited. Information regarding air pollutants was obtained from 151 environmental monitoring sites, and relative mtDNAcn was evaluated using real-time PCR analysis. After adjusting for potential confounding variables, it was determined that the risk of PTB increased with elevated levels of inhalable particulate matter (PM10), fine particulate matter (PM2.5), sulfur dioxide (SO2), carbon monoxide (CO) and ozone (O3) exposure (P < 0.05) but decreased with higher nitrogen dioxide (NO2) exposure (0.05 < P < 0.10) during the entire pregnancy. Additionally, the preconception relative mtDNAcn was lower in the PTB group (0.82 ± 0.23) compared to the term group (0.92 ± 0.29). Furthermore, for each 0.1-unit increase in preconception mtDNAcn, the risk of PTB decreased by 14.8%. Stratified analyses revealed that the risk of PTB rose with increasing O3 concentrations, regardless of the relative mtDNAcn. Moreover, the study found a significant association between PTB risk and prenatal exposure to elevated PM10, PM2.5, SO2, and CO, particularly in mothers with low mtDNAcn (≤0.88) (P < 0.05). Conversely, a decrease in the PTB risk was observed with elevated NO2 exposure in mothers with high mtDNAcn (>0.88). Interaction analysis revealed that exposure to PM10, PM2.5, SO2, NO2, and CO interacted with mtDNAcn, respectively, affecting PTB risk (P-interaction<0.05). These findings indicate a noteworthy association between PTB risk and prenatal air pollutants exposure, which is influenced by the preconception mtDNAcn.

The role of family history of preterm delivery in the individual risk of spontaneous preterm delivery: a case-control study

PURPOSE

To investigate the role of family history of preterm delivery (PTD) in the individual risk of spontaneous preterm delivery.

METHODS

A retrospective case-control study was conducted on 354 patients who delivered between 2018 and 2020. 177 women who delivered preterm were matched with 177 controls who had full-term delivery. A questionnaire was administered to investigate the family history of PTD of both the patient and her partner. Cases and controls were matched for the anamnestic risk factors for PTD.

RESULTS

Seventeen of 173 women (9.8%) in the PTD group reported being born preterm, compared to five of 169 women (2.9%) in the control group (p = 0.01), with an odds ratio (OR) of 3.57 (95% confidence interval, CI 1.29-9.92). Women who delivered preterm also reported more frequently having a sibling who was born preterm (12.4% vs. 4.2%, p = 0.01), with an OR of 3.18 (95% CI 1.31-7.7). No association was found between the partner's family history of premature delivery and the patient's risk of preterm delivery in the present pregnancy.

CONCLUSIONS

Pregnant patients who were born prematurely or who have siblings born preterm have an increased risk of preterm delivery in their own pregnancies. Assessment of female personal and family history of PTD should be used to identify women at risk of having a PTD in the present pregnancy.

Women's Economic Mobility and Small for Gestational Age Rates: The Effect of Paternal Early-Life Socioeconomic Position

OBJECTIVE

To determine whether paternal early-life socioeconomic position (defined by neighborhood income) modifies the association of maternal economic mobility and infant small for gestational age (weight for gestational age < 10th percentile, SGA) rates.

METHODS

Stratified and multilevel binomial regression analyses were executed on the Illinois transgenerational dataset of parents (born 1956-1976) and their infants (born 1989-1991) with appended U.S. census income information. Only Chicago-born women with an early-life residence in impoverished or affluent neighborhoods were studied.

RESULTS

The incidence of impoverished-born women's upward economic mobility among births (n = 3777) with early-life low socioeconomic position (SEP) fathers was less than that of those (n = 576) with early-life high SEP fathers: 56% vs 71%, respectively, p < 0.01. The incidence of affluent-born women's downward economic mobility among births (n = 2370) with early-life low SEP fathers exceeded that of those (n = 3822) with early-life high SEP fathers: 79% vs 66%, respectively, p < 0.01. The adjusted RR of infant SGA for maternal upward (compared to lifelong impoverishment) economic mobility among fathers with early-life low and high SEP equaled 0.68 (0.56, 0.82) and 0.81 (0.47, 1.42), respectively. The adjusted RR of infant SGA for maternal downward (compared to lifelong residence in affluent neighborhoods) economic mobility among fathers with early-life low and high SEP were 1.37 (0.91, 2.05) and 1.17 (0.86, 1.59), respectively.

CONCLUSIONS

Paternal early-life SEP is associated with maternal economic mobility (both upward and downward); however, it does not modify the relationship between maternal economic mobility and infant SGA rates.

Socioeconomic impacts on the intergenerational associations of preterm birth

BACKGROUND

The impact of socioeconomic status on intergenerational associations of preterm birth (PTB) is poorly understood.

OBJECTIVE

To estimate the socioeconomic status of intergenerational impact of PTB transmission.

STUDY DESIGN

This retrospective cohort study included all eligible singleton female infants born in Nebraska from 1995 to 2005 (n = 6631) and followed up from 2009 to 2019. Mothers' first singleton infants born 2009-2019 were linked to the mothers and included in the description and generalized estimating equations.

RESULTS

Mothers born PTB were 37% more likely to have a PTB infant after controlling for maternal and grandmother's prenatal care adequacy, maternal residential poverty, pre-pregnancy diabetes, hypertension, C-section, and infants' gender. In poor neighborhoods, the adjusted preterm odds ratio of former born preterm mothers (compared with mother not born PTB) was 1.56 (95% confidence interval (CI): 1.02, 2.38). Moreover, moving from a poor neighborhood to a relatively well-off neighborhood was a protective factor for PTB with an adjusted odds ratio of 0.47 (95% CI: 0.23, 0.95).

CONCLUSIONS

Mothers born preterm were at increased risk of having PTB infants, especially in poor areas. Maternal upward social mobility was a protective factor for PTB recurrence.

Postnatal persistence of cardiac remodeling and dysfunction in late fetal growth restriction

Fetal growth restriction is one of the most common obstetric complications, affecting 7-10% of all pregnancies. Affected fetuses are exposed to an adverse environment in utero during a critical time of development and may face long-term health consequences such as increased cardiovascular risk in adulthood. Growth restricted fetuses develop remodeled hearts with signs of systolic and diastolic dysfunction. Cardiac adaptations are more evident in early severe cases, but also present in late onset fetal growth restriction. Cardiovascular remodeling persists into postnatal life, from the neonatal period to adolescence, encompassing an increased susceptibility to adult disease. In this review, we summarize the current evidence on cardiovascular programming associated to fetal growth restriction, its postnatal consequences and potential strategies to reduce their cardiovascular risk.

Advanced maternal age impacts physiologic adaptations to pregnancy in vervet monkeys

The trend to delay pregnancy in the USA has resulted in the number of advanced maternal age (AMA) pregnancies to also increase. In humans, AMA is associated with a variety of pregnancy-related pathologies such as preeclampsia (PE). While AMA is known to be a factor which contributes to the development of pregnancy-induced diseases, the molecular and cellular mechanisms giving rise to this phenomenon are still very limited. This is due in part to lack of a preclinical model which has physiologic relevance to human pregnancy while also allowing control of environmental and genetic variability inherent in human studies. To determine potential physiologic relevance of the vervet/African green monkey (Chlorocebus aethiops sabaeus) as a preclinical model to study the effects of AMA on adaptations to pregnancy, thirteen age-diverse pregnant vervet monkeys (3-16 years old) were utilized to measure third trimester blood pressure (BP), complete blood count, iron measurements, and hormone levels. Significant associations were observed between third trimester diastolic BP and maternal age. Furthermore, the presence of leukocytosis with enhanced circulating neutrophils was observed in AMA mothers compared to younger mothers. Moreover, we observed a negative relationship between maternal age and estradiol, progesterone, and cortisol levels. Finally, offspring born to AMA mothers displayed a postnatal growth retardation phenotype. These studies demonstrate physiologic impairment in the adaptation to pregnancy in AMA vervet/African green monkeys. Our data indicate that the vervet/African green monkey may serve as a useful preclinical model and tool for deciphering pathological mediators of maternal disease in AMA pregnancy.

Educational Attainment of Grandmothers and Preterm Birth in Grandchildren

BACKGROUND

Maternal education has been shown repeatedly to be inversely associated with preterm birth. Both preterm birth and educational level of families are correlated across generations, but it is not clear if educational level of grandparents affects the risk of preterm delivery of their grandchildren, and, if so, if the association with grandmother's education is independent of mother's education.

METHODS

We used New Jersey birth certificates to create a transgenerational dataset to examine the effect of grandmother's education on risk of PTB in White, Black and Hispanic grandchildren. We matched birth certificates of girls born in 1979-1983 to mothers listed on NJ birth certificates for the years 1999-2011. Thus, grandmothers were the women delivering in 1979-1983, and mothers were those born to the grandmothers who in turn delivered grandchildren in 1999-2011. We performed descriptive tabulations and multivariate logistic regression to develop risk estimates.

RESULTS

Overall, maternal education was associated inversely with PTB in each of the demographic groups. There was a substantial inter-generational increase in education between grandmothers and mothers in each group, which was most striking in Hispanics After adjusting for maternal age and education, grandmother's education continued to be associated with preterm birth of her grandchildren.

CONCLUSIONS

Grandmother's education was an additional, independent predictor of PTB in her grandchildren. This result supports the idea that mother's childhood and preconception socioeconomic environment, including the educational level of her childhood household affect her reproductive health.

Adverse birth outcome across the generations: the contribution of paternal factors

PURPOSE

There is literature suggesting an intergenerational relationship between maternal and infant size for gestational age status and preterm birth, but much less is known about the contribution of paternal birth outcome to infant birth outcome. This study seeks to determine the association between paternal and infant small-for-gestational-age status (weight for gestational age < 10th percentile, SGA) and preterm birth (< 37 weeks gestation, PTB) in a large, diverse population-based sample in the United States.

METHODS

Stratified and log-binomial multivariable regression analyses were computed on the vital records of Illinois-born infants (1989-1991) and their Illinois-born parents (born 1956-1976).

RESULTS

Among non-Hispanic Whites (n = 83,218), the adjusted (controlling for maternal SGA or PTB, age, parity, education, marital status, prenatal care, and cigarette smoking) relative risk (95% confidence interval) of infant SGA and PTB for former SGA (compared to non-SGA) and preterm (compared to term) fathers equaled 1.65 (1.53, 1.77) and 1.07 (0.92, 1.24), respectively. Among African-Americans (n = 8401), the adjusted relative risk (95% confidence interval) of infant SGA and PTB for former SGA (compared to non-SGA) and preterm (compared to term) fathers equaled 1.32 (1.14, 1.52) and 1.19 (0.98, 1.45), respectively.

CONCLUSION

Paternal adverse birth outcome, particularly SGA, is a modest risk factor for corresponding adverse infant outcome, independent of maternal risk status. This phenomenon appears to occur similarly among non-Hispanic White and African-American women.

Importance of the environment for gestational duration variability and correlation between relatives - results from the Medical Swedish Birth Registry, 1973-2012

It has been suggested that the intergenerational associations in gestational age at delivery are considerably affected by temporal changes in the environmental conditions. We explored whether changing environment affects familial resemblance of gestational age at delivery. Understanding how correlation changes in different settings allows to design better studies aimed to detect genes and environmental factors involved in the parturition process. The Swedish Medical Birth Register was used to retrieve births during 1973–2012. In total, 454,433 parent-child, 2,247,062 full sibling, 405,116 maternal half-sibling and 469,995 paternal half-sibling pairs were identified. A decreasing trend in correlation, associated with increasing age gaps, was observed among all siblings, with the largest drop for full siblings, from ρ = 0.32 (95% confidence interval (CI): 0.31, 0.33) for full siblings with one-year gap to ρ = 0.16 (95% CI: 0.10, 0.22) for full siblings with age gap above 20 years. A variation in association between full siblings born up to two years apart was observed; estimate ρ = 0.28 (95% CI: 0.26, 0.3) in 1973, and ρ = 0.36 (95% CI: 0.33, 0.38) in 2012. Observed variability in the association in gestational age at delivery between the relatives with respect to their birth year or age gap suggests the existence of temporally changing environmental factors.

Non-Hispanic White Women's Exposure to Decreased Neighborhood Income and Small for Gestational Age Births: A Population-Based Study

BACKGROUND

The relationship between non-Hispanic White (NHW) women's decreased neighborhood income between early-life and adulthood, individual risk-status at delivery, and small for gestational age (weight for gestation < 10th percentile, SGA) rates is unknown.

OBJECTIVE

To determine the extent to which NHW women's exposure to decreased neighborhood income is a risk factor for SGA births, and whether their own birth weight modifies this relationship.

METHODS

Stratified and multilevel logistic regression analyses were executed on the Illinois transgenerational dataset of mothers (born 1956-1976) and their infants (born 1989-1991) with appended U.S. census income information. Only NHW women with an early-life residence in top income quartile Chicago neighborhoods were studied.

RESULTS

NHW women (n = 4889) unexposed to decreased neighborhood income between early-life and adulthood had an SGA rate of 7.1%. In contrast, NHW women exposed to slightly (n = 5112), modestly (n = 2158), or severely (n = 339) decreased neighborhood income by the time of delivery had SGA rates of 8.2%, 10.8%, and 10.8%, respectively; RR (95% CI) equaled 1.2 (1.0-1.3), 1.5 (1.3-1.8) and 1.5 (1.1-2.1), respectively. The relationship between maternal exposure to modestly decreased neighborhood income and SGA rates was present only among former non-low birth weight (> 2500 g, non-LBW) mothers. In multilevel logistic regression models, the adjusted (controlling for age, parity, prenatal care usage, and cigarette smoking) OR of SGA birth for former low birth weight (< 2500 g, LBW) and non-LBW NHW women exposed to modestly (compared to no) decreased neighborhood income equaled 0.7 (0.4, 1.4) and 1.3 (1.1-1.6), respectively.

CONCLUSIONS FOR PRACTICE

NHW women's exposure to modestly decreased neighborhood income is associated with an increased risk of SGA birth; this phenomenon is absent among former low birth weight women.

The color of health: how racism, segregation, and inequality affect the health and well-being of preterm infants and their families

Racism, segregation, and inequality contribute to health outcomes and drive health disparities across the life course, including for newborn infants and their families. In this review, we address their effects on the health and well-being of newborn infants and their families with a focus on preterm birth. We discuss three causal pathways: increased risk; lower-quality care; and socioeconomic disadvantages that persist into infancy, childhood, and beyond. For each pathway, we propose specific interventions and research priorities that may remedy the adverse effects of racism, segregation, and inequality. Infants and their families will not realize the full benefit of advances in perinatal and neonatal care until we, collectively, accept our responsibility for addressing the range of determinants that shape long-term outcomes.

Racial disparities in the transgenerational transmission of low birthweight risk

Objective: To examine the association of maternal low birthweight (LBW) with infant LBW and infant LBW subgroups (i.e. moderate and very LBW), overall and among non-Hispanic (NH) white and NH black mothers. Design: We conducted a population-based cohort study in Allegheny County, Pennsylvania, using linked birth record data of NH white and NH black mother-infant pairs (N = 6,633) born in 1979-1998 and 2009-2011, respectively. The exposure of interest was maternal LBW (birthweight <2500 grams) while the outcomes were infant LBW and LBW subgroups - moderate LBW (1,500-2,499 grams) or very LBW (<1,500 grams). Logistic regression (binomial and multinomial) models were used to estimate adjusted Odds Ratios (ORs), Relative Risk Ratios (RRRs), and related 95% confidence intervals (CI). Stratified analyses were conducted to assess effect modification by mothers' race. Results: Maternal LBW was associated with 1.53 (95%CI: 1.15-2.02) and 1.75 (95%CI: 1.29-2.37) -fold increases in risk of infant LBW and MLBW, respectively, but not VLBW (RRR = 0.86; 95%CI: 0.44-1.70). In race-stratified models, maternal LBW-infant LBW associations were observed among NH blacks (OR = 1.88; 95%CI: 1.32-2.66) and not among NH whites (OR = 1.03; 95%CI: 0.62-1.73) (P for interaction = 0.07). Among NH blacks, maternal LBW was associated with a 2.18 (95%CI: 1.49, 3.20) -fold increase in risk of infant MLBW, but not VLBW (RRR = 1.12; 95%CI: 0.54, 2.35). Among NH whites, LBW subgroup analyses could not be performed due to small numbers of VLBW infants among LBW mothers. Conclusion: Mothers who were LBW at their own birth were more likely to have MLBW infants. Maternal race modified associations of maternal LBW with infant LBW, particularly infant MLBW. Further research is needed in this area to understand the potential mechanisms involved in the transgenerational transmission of LBW risk and race-specific differences in the transmission.

Socioeconomic Status, Preeclampsia Risk and Gestational Length in Black and White Women

BACKGROUND

Higher socioeconomic status (SES) has less impact on cardio-metabolic disease and preterm birth risk among Black women compared to White women, an effect called "diminishing returns." No studies have tested whether this also occurs for pregnancy cardio-metabolic disease, specifically preeclampsia, or whether preeclampsia risk could account for race-by-SES disparities in birth timing.

METHODS

A sample of 718,604 Black and White women was drawn from a population-based California cohort of singleton births. Education, public health insurance status, gestational length, and preeclampsia diagnosis were extracted from a State-maintained birth cohort database. Age, prenatal care, diabetes diagnosis, smoking during pregnancy, and pre-pregnancy body mass index were covariates.

RESULTS

In logistic regression models predicting preeclampsia risk, the race-by-SES interaction (for both education and insurance status) was significant. White women were at lower risk for preeclampsia, and higher SES further reduced risk. Black women were at higher risk for preeclampsia, and SES did not attenuate risk. In pathway analyses predicting gestational length, an indirect effect of the race-by-SES interaction was observed. Among White women, higher SES predicted lower preeclampsia risk, which in turn predicted longer gestation. The same was not observed for Black women.

CONCLUSIONS

Compared to White women, Black women had increased preeclampsia risk. Higher SES attenuated risk for preeclampsia among White women, but not for Black women. Similarly, higher SES indirectly predicted longer gestational length via reduced preeclampsia risk among White women, but not for Black women. These findings are consistent with diminishing returns of higher SES for Black women with respect to preeclampsia.

Allostatic load, a measure of chronic physiological stress, is associated with pregnancy outcomes, but not fertility, among women with unexplained infertility

STUDY QUESTION

Among infertile women undergoing ovarian stimulation, is allostatic load (AL), a measure of chronic physiological stress, associated with subsequent fertility and pregnancy outcomes?

SUMMARY ANSWER

AL at baseline was not associated with conception, spontaneous abortion or live birth, however, it was significantly associated with increased odds of pre-eclampsia and preterm birth among women who had a live birth in the study.

WHAT IS KNOWN ALREADY

Several studies have linked AL during pregnancy to adverse outcomes including preterm birth and pre-eclampsia, hypothesizing that it may contribute to well-documented disparities in pregnancy and birth outcomes. However, AL biomarkers change over the course of pregnancy, raising questions as to whether gestational AL assessment is a valid measure of cumulative physiologic stress starting long before pregnancy. To better understand how AL may impact reproductive outcomes, AL measurement in the non-pregnant state (i.e. prior to conception) is needed.

STUDY DESIGN, SIZE, DURATION

A secondary data analysis based on data from 836 women who participated in Assessment of Multiple Intrauterine Gestations from Ovarian Stimulation (AMIGOS), a multi-center, randomized clinical trial of ovarian stimulation conducted from 2011 to 2014.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Ovulatory women with unexplained infertility (ages 18-40) were enrolled and at baseline, biological and anthropometric measures were collected. AL scores were calculated as a composite of the following baseline variables determined a priori: BMI, waist-to-hip ratio, systolic blood pressure, diastolic blood pressure, dehydroepiandrosterone sulfate, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, C-reactive protein and HOMA score. Participants received ovarian stimulation for up to four cycles and if they conceived, were followed throughout pregnancy. We fit multi-variable logistic regression models examining AL (one-tailed and two-tailed) in relation to the following reproductive outcomes: conception, spontaneous abortion, live birth, pre-eclampsia, preterm birth and low birthweight.

MAIN RESULTS AND THE ROLE OF CHANCE

Adjusting for covariates, a unit increase in two-tailed AL score was associated with 62% increased odds of pre-eclampsia (OR: 1.62, 95% CI: 1.14, 2.38) 44% increased odds of preterm birth (OR: 1.44, 95% CI: 1.02, 2.08), and 39% increased odds of low birthweight (OR: 1.39, 95% CI: 0.99, 1.97). The relationship between AL and preterm birth was mediated by pre-eclampsia (P = 0.0003). In one-tailed AL analyses, associations were similar, but slightly attenuated. AL was not associated with fertility outcomes (conception, spontaneous abortion, live birth).

LIMITATIONS, REASONS FOR CAUTION

Results may not be generalizable to fertile women who conceive naturally or women with other types of infertility. Comparisons to previous, related work are difficult because variables included in AL composite measures vary across studies. AL may be indicative of overall poor health, rather than being specific to chronic physiological stress.

WIDER IMPLICATIONS OF THE FINDINGS

Our results suggest that chronic physiological stress may not impact success of ovarian stimulation, however, they confirm and extend previous work suggesting that AL is associated with adverse pregnancy outcomes. Physiological dysregulation due to chronic stress has been proposed as a possible mechanism underlying disparities in birth outcomes, which are currently poorly understood. Assessing biomarkers of physiological dysregulation pre-conception or in early pregnancy, may help to identify women at risk of adverse pregnancy outcomes, particularly pre-eclampsia.

STUDY FUNDING/COMPETING INTEREST(S)

Support for AMIGOS was provided by: U10 HD39005, U10 HD38992, U10 HD27049, U10 HD38998, U10 HD055942, HD055944, U10 HD055936 and U10HD055925. Support for the current analysis was provided by T32ES007271, R25HD075737, P30ES001247 and P30ES005022. This research was made possible by funding by American Recovery and Reinvestment Act. The content is solely the responsibility of the authors and does not necessarily represent the official views of NICHD, NIEHS or NIH. E.B., W.V., O.M., R.A., M.R., V.B., G.W.B., C.C., E.E., S.K., R.U., P.C, H.Z., N.S. and S.T. have nothing to disclose. R.L. reported serving as a consultant to Abbvie, Bayer, Kindex, Odega, Millendo and Fractyl and serving as a site investigator and receiving grants from Ferring. K.H. reported receiving grants from Roche Diagnostics and Ferring. R.R. reported a grant from AbbVie. M.D. reported being on the Board of Directors of and a stockholder in Advanced Reproductive Care.

TRIAL REGISTRATION NUMBER

Clinical Trials.gov number: NCT01044862.

Transgenerational transmission of small-for-gestational age

OBJECTIVE

To evaluate the transgenerational transmission of small-for-gestational age (SGA).

METHODS

This was a cohort study of a random sample of 2043 offspring delivered between 1975 and 1993 at Hospital Sant Joan de Déu in Barcelona. Exclusion criteria were multiple pregnancy, aneuploidy or genetic syndrome, major birth defects, severe mental disease and macrosomia. Eligible individuals were contacted and those with at least one offspring were included in the study. Participants were classified according to the presence of SGA (defined as birth weight < 10^th percentile) at birth. Multiple regression analysis was used to determine the presence of SGA or placenta-mediated disease (defined as the presence of SGA, pre-eclampsia, gestational hypertension and/or placental abruption) in the following generation.

RESULTS

Of 623 individuals who agreed to participate, 152 (72 born SGA and 80 born appropriate-for-gestational age (AGA)) were reported to have at least one child. Descendants of SGA individuals presented with a lower birth-weight percentile (median, 26 (interquartile range (IQR), 7-52) vs 43 (IQR, 19-75); P < 0.001) and a higher prevalence of SGA (40.3% vs 16.3%; P = 0.001) and placenta-mediated disease (43.1% vs 17.5%; P = 0.001) than did the offspring of AGA individuals. After adjustment for confounding variables, parental SGA background was associated with an almost three-fold increased risk of subsequent SGA or any placenta-mediated disease in the following generation. This association was stronger in SGA mothers than in SGA fathers.

CONCLUSIONS

Our data provide evidence suggesting a transgenerational transmission of SGA, highlighting the importance of public health strategies for preventing intrauterine growth impairment. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Low Birth Weight Among Infants Born to Black Latina Women in the United States

Objectives To explore associations between race, nativity, and low birth weight (LBW) among Latina and non-Latina women, with special attention to the Black Latina subgroup. Methods Using US natality data from 2011 to 2013, we designed a population-based study to compare LBW (< 2500 g) rates across six groups of women with self-identified race (N = 7,865,264)-White and Black Latina, foreign-born and US-born; non-Latina Black; and non-Latina White-creating 4 models for analysis: unadjusted (Model 1) and adjusted for sociodemographic factors (Model 2), sociodemographic plus medical risk factors (Model 3), and Model 3 factors plus smoking (Model 4). Results Infant LBW rate for Black Latinas (7.9%) was higher than White Latinas (5.6%) and varied by nativity: US-born (8.9%) versus foreign-born (6.1%). Among all study groups, US-born Black Latinas' LBW rate (8.9%) was second only to non-Latina Blacks (11.0%). In unadjusted Model 1, US-born Black Latinas had 81% (odds ratio [OR]: 1.81; 95% confidence interval [CI]: 1.74-1.88) and foreign-born Black Latinas had 22% (OR: 1.22; 95% CI 1.15-1.29) higher odds of LBW than non-Latina White women (reference group). However, in Model 2, ORs for foreign-born Black Latinas were nearly identical to non-Latina Whites (OR: 1.03; 95% CI 0.97-1.1), while US-born Black Latinas' odds were still 47% higher (OR: 1.47; 95% CI 1.42-1.53). Model 3 ORs for each group were similar to Model 2. Conclusions for Practice A significant subgroup of Latina women self-identify as Black, and their LBW rates are higher than White Latinas. Black Latinas born in the United States fare worse than their foreign-born counterparts, implicating negative effects of Black race specific to the US context.

African-American women's Upward Economic Mobility and Small for Gestational Age Births: A Population-Based Study

Background The relationship between African-American women's upward economic mobility and small for gestational age (weight for gestational < 10th percentile, SGA) rates is incompletely understood. Objective To ascertain the extent to which African-American women's upward economic mobility from early-life impoverishment is coupled with reduced SGA rates. Methods Stratified and multilevel logistic regression analyses were completed on the Illinois transgenerational dataset of African-American infants (1989-1991) and their Chicago-born mothers (1956-1976) with linked U.S. census income information. Results Impoverished-born (defined as lowest quartile of neighborhood income distribution) African-American women (n = 4891) who remained impoverished by the time of delivery had a SGA rate of 19.7%. Individuals who achieved low (n = 5827), modest (n = 2254), or high (n = 732) upward economic mobility by adulthood had lower SGA rates of 17.2, 14.8, and 13.7%, respectively; RR = 0.9 (0.8-0.9), 0.8 (0.7-0.8), and 0.7 (0.6-0.8), respectively. In adjusted (controlling for traditional individual-level risk factors) multilevel regression models, there was a decreasing linear trend in SGA rates with increasing levels of upward economic mobility; the adjusted RR of SGA birth for impoverished-born African-American women who experienced low, modest, of high (compared to no) upward mobility equaled 0.95 (0.91, 0.99), 0.90 (0.83, 0.98), and 0.86 (0.75, 0.98), respectively, p < 0.05. Conclusions African-American women's upward economic mobility from early-life residence in poor urban communities is associated with lower SGA rates independent of adulthood risk status.

Father's Lifetime Socioeconomic Status, Small for Gestational Age Infants, and Infant Mortality: A Population-Based Study

Objective

To ascertain the association between father's lifetime socioeconomic status (SES) and rates of small for gestational age (SGA, defined as weight for gestational age <10th percentile) and infant mortality (defined as <365 days).

Methods

The study sample was limited to the singleton births of African American (n=8,331), non-Latina White (n=18,200), and Latina (n=2,637) women. Stratified and multilevel, multivariable logistic regression analyses were conducted on the Illinois transgenerational dataset of infants (1989-1991) and their Chicago-born parents (1956-1976) with appended US census income data (n=29,168). The median family income of father's census tract residence during childhood and parenthood were used to assess lifetime SES.

Results

Births (n=8,113) to fathers with a lifetime low SES had a SGA rate of 13.3% compared with 6.6% for those (n=10,329) born to fathers with a lifetime high SES, RR = 1.97 (1.79, 2.17). The infant mortality rate of births to fathers with a lifetime low SES exceeded that of infant mortality rate of births to fathers with a lifetime high SES: 13/1,000 vs 5/1,000, respectively; RR = 2.71 (1.94, 3.77). The adjusted (controlling for mother's age, education, marital status, and race/ethnicity) OR of SGA for fathers with childhood, parenthood, and lifetime low (vs high) SES were 1.15 (1.01, 1.31), 1.13 (1.02, 1.26), and 1.19 (1.05, 1.34), respectively. The adjusted OR of infant mortality for births to fathers with childhood, parenthood, and lifetime low (vs high) SES were 1.14 (.78, 1.67), 1.40 (.90, 2.18), and 1.31 (.90, 1.92), respectively.

Conclusions

Low paternal socioeconomic status is a previously unrecognized determinant of SGA birth regardless of mother's demographic status.

The South Carolina Multigenerational Linked Birth Dataset: Developing Social Mobility Measures Across Generations to Understand Racial/Ethnic Disparities in Adverse Birth Outcomes in the US South

Objectives To describe the creation of a multigenerational linked dataset with social mobility measures for South Carolina (SC), as an example for states in the South and other areas of the country. Methods Using unique identifiers, we linked birth certificates along the maternal line using SC birth certificate data from 1989 to 2014, and compared the subset of records for which linking was possible with two comparison groups on sociodemographic and birth outcome measures. We created four multi-generational social mobility measures using maternal education, paternal education, presence of paternal information, and a summary score incorporating the prior three measures plus payment source for births after 2004. We compared social mobility measures by race/ethnicity. Results Of the 1,366,288 singleton birth certificates in SC from 1989 to 2014, we linked 103,194, resulting in 61,229 unique three-generation units. Mothers and fathers were younger and had lower education, and low birth weight was more common, in the multigenerational linked dataset than in the two comparison groups. Based on the social mobility summary score, only 6.3% of White families were always disadvantaged, compared to 30.4% of Black families and 13.2% of Hispanic families. Moreover, 32.8% of White families were upwardly mobile and 39.1% of Black families were upwardly mobile, but only 29.9% of Hispanic families were upwardly mobile. Conclusions for Practice When states are able to link individuals, birth certificate data may be an excellent source for examining population-level relationships between social mobility and adverse birth outcomes. Due to its location in the Deep South, the multigenerational SC dataset may be particularly useful for understanding racial/ethnic difference in social mobility and birth outcomes.

Intergenerational Transmission of Birth Weight Across 3 Generations

While previous studies have shown intergenerational transmission of birth weight from mother to child, whether the continuity persists across 3 generations has rarely been assessed. We used the Aberdeen Maternity and Neonatal Databank (United Kingdom) to examine the intergenerational correlations of birth weight, birth weight adjusted for gestational age and sex, and small- and large-for-gestational-age births across 3 generations among 1,457 grandmother-mother-child triads. All participants were born between 1950 and 2015. The intergenerational transmission was examined with linear regression analyses. We found that grandmaternal birth weight was associated with grandchild birth weight, independently of prenatal and sociodemographic covariates and maternal birth weight (B = 0.12 standard deviation units, 95% confidence interval: 0.07, 0.18). Similar intergenerational continuity was found for birth weight adjusted for sex and gestational age as well as for small-for-gestational-age births. In conclusion, birth weight and fetal growth showed intergenerational continuity across 3 generations. This supports the hypothesis that the developmental origins of birth weight and hence later health and disease are already present in earlier generations.

Association between race/skin color and premature birth: a systematic review with meta-analysis

OBJECTIVE

To analyze the association between race/skin color and the occurrence of prematurity.

METHODS

Meta-analysis with observational studies, selected by a systematic review in the bibliographic databases Medline and Biblioteca Virtual da Saúde with the descriptors: “Race or ethnic group” and “ethnicity and health” associated with the words “infant premature” and “obstetric labor premature”. Articles published in the period from 2010 to 2014, of the observational epidemiological type, in Portuguese, English and Spanish, were included. Articles that did not have abstracts or that were review articles, theses, dissertations, and editorials were excluded. We adopted the relative risk and their respective confidence intervals (95%CI) as measures of effect, obtained through the random effect model and represented by the forest plot type graph. The Egger test and the Newcastle-Ottawa scale, respectively, were used to analyze possible publication biases and the quality of the studies.

RESULTS

Of the 926 articles identified, 17 were eligible for the study. Of the 17 full texts published, seven were retrospective cohort studies, nine were cross-sectional studies, and one was a case-control study. Except for one study, the others reported a positive association between race/color of skin and prematurity. Compared with full-term newborns, the relative risk of the combined effect in those born preterm was 1.51 (95%CI 1.39-1.69). The funnel chart suggested publication bias.

CONCLUSIONS

The present meta-analysis indicated a positive association for the risk of prematurity according to race/skin color.

Maternal race and intergenerational preterm birth recurrence

BACKGROUND

Preterm birth is a complex disorder with a heritable genetic component. Studies of primarily White women born preterm show that they have an increased risk of subsequently delivering preterm. This risk of intergenerational preterm birth is poorly defined among Black women.

OBJECTIVE

Our objective was to evaluate and compare intergenerational preterm birth risk among non-Hispanic Black and non-Hispanic White mothers.

STUDY DESIGN

This was a population-based retrospective cohort study, using the Virginia Intergenerational Linked Birth File. All non-Hispanic Black and non-Hispanic White mothers born in Virginia 1960 through 1996 who delivered their first live-born, nonanomalous, singleton infant ≥20 weeks from 2005 through 2009 were included. We assessed the overall gestational age distribution between non-Hispanic Black and White mothers born term and preterm (<37 weeks) and their infants born term and preterm (<37 weeks) using Cox regression and Kaplan-Meier survivor functions. Mothers were grouped by maternal gestational age at delivery (term, ≥37 completed weeks; late preterm birth, 34-36 weeks; and early preterm birth, <34 weeks). The primary outcomes were: (1) preterm birth among all eligible births; and (2) suspected spontaneous preterm birth among births to women with medical complications (eg, diabetes, hypertension, preeclampsia and thus higher risk for a medically indicated preterm birth). Multivariable logistic regression was used to estimate odds of preterm birth and spontaneous preterm birth by maternal race and maternal gestational age after adjusting for confounders including maternal education, maternal age, smoking, drug/alcohol use, and infant gender.

RESULTS

Of 173,822 deliveries captured in the intergenerational birth cohort, 71,676 (41.2%) women met inclusion criteria for this study. Of the entire cohort, 30.0% (n = 21,467) were non-Hispanic Black and 70.0% were non-Hispanic White mothers. Compared to non-Hispanic White mothers, non-Hispanic Black mothers were more likely to have been born late preterm (6.8% vs 3.7%) or early preterm (2.8 vs 1.0%), P < .001. Non-Hispanic White mothers who were born (early or late) preterm were not at an increased risk of early or late preterm delivery compared to non-Hispanic White mothers born term. The risk of early preterm birth was most pronounced for Black mothers who were born early preterm (adjusted odds ratio, 3.26; 95% confidence interval, 1.77-6.02) compared to non-Hispanic White mothers.

CONCLUSION

We found an intergenerational effect of preterm birth among non-Hispanic Black mothers but not non-Hispanic White mothers. Black mothers born <34 weeks carry the highest risk of delivering their first child very preterm. Future studies should elucidate the underlying pathways leading to this racial disparity.

Transgenerational Transmission of Preterm Birth Risk: The Role of Race and Generational Socio-Economic Neighborhood Context

Objectives We investigated associations of mothers' preterm birth (PTB) status with her infants' PTB risk. We also examined whether this relationship differs by mothers' race and generational socio-economic neighborhood context. Methods Participants were 6592 non-Hispanic (NH) white and NH black mother-infant pairs born in 2009-2011 and 1979-1998, respectively, in Allegheny County, Pennsylvania. Birth records were used to determine gestational age at birth, PTB status (<37 completed weeks of gestation), and PTB subgroups-late and early PTB (34-36 weeks and <34 completed weeks of gestation, respectively). Census data on tract racial composition and household income were used to characterize residential race and economic environment. Logistic regression models were used to calculate Odds Ratios (ORs), Relative Risk Ratios (RRR), and 95% confidence intervals (CIs). Stratified analyses were conducted to assess effect modification. Results Overall, 8.21, 6.63 and 1.58% infants had PTB, LPTB, and EPTB, respectively. Maternal PTB status was associated with a 46% increase in infant PTB (95% CI: 1.08-1.98), EPTB (95% CI: 0.80-2.69), and LPTB (95% CI: 1.04-2.04) risk. Maternal PTB-infant PTB associations, particularly maternal PTB-infant LPTB associations, were stronger among NH blacks, mothers in neighborhoods with a high percentage of NH black residents in both generations, or mothers who moved to neighborhoods with a higher percentage of NH black residents. Conclusions for Practice Race and generational socio-economic neighborhood context modify transgenerational transmission of PTB risk. These findings are important for identification of at-risk populations and to inform future mechanistic studies.

Epigenetics: linking social and environmental exposures to preterm birth

Preterm birth remains a leading cause of infant mortality and morbidity. Despite decades of research, marked racial and socioeconomic disparities in preterm birth persist. In the Unites States, more than 16% of African-American infants are born before 37 wk of gestation compared with less than 11% of white infants. While income and education differences predict a portion of these racial disparities, income and education are proxies of the underlying causes rather than the true cause. How these differences lead to the pathophysiology remains unknown. Beyond tobacco smoke exposure, most preterm birth investigators overlook environment exposures that often correlate with poverty. Environmental exposures to industrial contaminants track along both socioeconomic and racial/ethnic lines due to cultural variation in personal product use, diet, and residential geographical separation. Emerging evidence suggests that environmental exposure to metals and plasticizers contribute to preterm birth and epigenetic modifications. The extent to which disparities in preterm birth result from interactions between the social and physical environments that produce epigenetic modifications remains unclear. In this review, we highlight studies that report associations between environmental exposures and preterm birth as well as perinatal epigenetic sensitivity to environmental contaminants and socioeconomic stressors.