Twin births in Yucatan, Mexico during 2008-2020: trends in maternal sociodemographic factors and differences in birth weight and length according to sex of co-twin

Background: Over the years, there has been a noticeable increase in the incidence of multiple pregnancies, due in part to the increased use of assisted reproductive technologies in recent years. The increase in twin pregnancies constitutes a public health challenge due to the adverse outcomes sometimes they entail. Twin pregnancies inherently carry a higher risk of complications, and one of the critical associated factors is the risk of low birth weight. Twin birth weight discordance among different populations can be attributed to differences in non-shared environmental influences. The presence of two or more fetuses in the uterus may lead to an unequal distribution of nutritional and oxygen resources, increasing the likelihood that at least one of the twins will experience insufficient fetal development. Other factors, such as ethnicity, genetics, sociodemographic characteristics, gestational age, parity, and chorion type, have also been related to the birth weight discordance in twin pregnancies. However, it is unclear to what extent the associations between these factors can explain the differences in birth and length size. The frequency of twin births varies among populations and over time, so it is crucial to gain a deeper understanding of the factors contributing to the rise in the twinning rate. The official records of twins continue to make significant contributions to our understanding of the causes of individual differences, and new twin registries are still being created. The recent availability of data from developing countries allows the analysis of trends in regions with sociodemographic and reproductive profiles. Obtaining a more comprehensive understanding of the epidemiology, as well as the related morbidity and mortality, is clinically crucial. Objectives: The aim of the study was to describe the trends of twin births in Yucatan, Mexico during 2008-2021, analyze their association with maternal sociodemographic factors, and compare birth outcomes between types of twin pairs: female-female, male-male, and female-male. Methods: A retrospective cohort analysis was conducted using data from the Mexican Ministry of Health, encompassing information on all births registered in the State of Yucatán, Mexico, from 2008 through 2021. The data was obtained from both public and private hospitals. The variables, including date of birth, sex, gestational age, birth weight and length of newborns, mother´s date of birth, educational level, and number of previous live offspring, were extracted from each dataset. Multiple births (three or more) were excluded from the study. We graphically analyzed the rates (per 1000 births) and percentages of twins according to maternal age, education level, and parity during the study period. A multiple logistic regression model was used to analyze the association between maternal sociodemographic factors and the occurrence of twin births. Comparisons of the gestational age and birth weight and length between types of twin pairs were performed using analysis of variance. Results: A total of 478,118 live births, including 1.4% twins (accounting 6,766 twin births), were analyzed. The rates increased from 11.21 during 2008-2011 to 13.34 during 2012-2017 and reached 20.08 in 2019. The percentages increased in women aged ≥30 years and those with higher educational levels. Older maternal age (coefficient = 0.03; OR = 1.03, per each year), greater education level (coefficient = 0.55 and OR= 1.74 for medium and coefficient = 1.05; OR = 2.57 for high level, compared with no education) and higher parity (coefficient= 0.26; OR = 1.30 per each previous offspring) increased the odds for having twins. Twins' male-male showed a slightly increased of preterm birth than a co-twin female. Opposite-sex twins showed measurable but small increases in birth weight and length compared with same-sex twins. Conclusion: The rate of twins in Yucatan increased substantially during 2008-2020 in specific sociodemographic groups. Opposite-sex twins were slightly larger than same-sex twins at birth.

Epidemiology of rhabdoid tumors of early childhood

BACKGROUND

Rhabdoid tumors are a rare and aggressive cancer subtype which is usually diagnosed in early childhood. Little is known about their etiology. The purpose of this study was to describe the epidemiology of rhabdoid tumors and examine their relation to perinatal characteristics.

METHODS

We identified 44 atypical teratoid/rhabdoid tumors (AT/RT) of the central nervous system (CNS) and 61 rhabdoid sarcomas (renal and extra-renal non-CNS tumors) from California Cancer Registry records of diagnoses 1988-2007 among children <6 years of age. We randomly selected 208,178 controls from California birthrolls. Multivariable logistic regression was used to examine associations between rhabdoid tumors and perinatal characteristics.

RESULTS

After adjustment for demographic characteristics, low birthweight (<2,500 g) strongly increased risk for developing both rhabdoid sarcomas (OR = 2.43, 95% CI 1.09, 5.41) and AT/RT (OR = 2.99, 95% CI 1.31, 6.84). Both preterm delivery (<37 weeks gestation, OR = 2.63, 95% CI 1.34, 5.17) and late term delivery (>42 weeks, OR = 3.66, 95% CI 1.54, 8.71) also increased risk of rhabdoid sarcomas. Rhabdoid sarcoma cases (OR = 3.08, 95% CI 1.11, 8.55) and AT/RT cases (OR = 3.16, 95% CI 1.23, 8.13) also were more likely to be multiple births.

CONCLUSION

The excess of twin pregnancies may suggest an association with infertility treatments. This is the first population-based epidemiologic study to examine these rare tumors.

Early-life exposures and early-onset uterine leiomyomata in black women in the Sister Study

BACKGROUND

Uterine leiomyomata (fibroids) are hormonally responsive tumors, but little is known about risk factors. Early-life exposures may influence uterine development and subsequent response to hormones in adulthood. An earlier analysis of non-Hispanic white women who participated in the Sister Study found associations between several early-life factors and early-onset fibroids.

OBJECTIVES

We evaluated associations of early-life and childhood exposures with early-onset fibroids among black women and compared the results with those found among white women.

METHODS

We analyzed baseline data from 3,534 black women, 35-59 years of age, in the Sister Study (a nationwide cohort of women who had a sister diagnosed with breast cancer) who self-reported information on early-life and childhood exposures. Early-onset fibroids were assessed based on self-report of a physician diagnosis of fibroids by the age of 30 years (n = 561). We estimated risk ratios (RR) and 95% confidence intervals (CI) from log-binomial regression models.

RESULTS

Factors most strongly associated with early-onset fibroids were in utero diethylstilbestrol (DES; RR = 2.02; 95% CI: 1.28, 3.18), maternal prepregnancy diabetes or gestational diabetes (RR = 1.54; 95% CI: 0.95, 2.49), and monozygotic multiple birth (RR = 1.94; 95% CI: 1.26, 2.99). We also found positive associations with having been taller or thinner than peers at the age of 10 years and with early-life factors that included being the firstborn child of a teenage mother, maternal hypertensive disorder, preterm birth, and having been fed soy formula.

CONCLUSIONS

With the exception of monozygotic multiple birth and maternal hypertensive disorder, early-life risk factors for early-onset fibroids for black women were similar to those found for white women. However, in contrast to whites, childhood height and weight, but not low socioeconomic status indicators, were associated with early-onset fibroids in blacks. The general consistency of early-life findings for black and white women supports a possible role of early-life factors in fibroid development.