Does changing paternity contribute to the risk of intrauterine growth retardation?

Does recurrent gestational diabetes mellitus increase the risk of preterm birth? A population-based cohort study

AIMS

To investigate whether recurrent gestational diabetes mellitus (GDM) is associated with an increased risk of preterm birth.

METHODS

We conducted a prospective population-based cohort study covering all live singleton births born to nulliparous and multiparous mothers aged 20 years and older in Qingdao, from 2018 to 2020 (n = 105,528). Preterm birth (<37 gestational weeks) was classified into moderate preterm birth (32-36 weeks of gestation) and very preterm birth (<32 weeks). Logistic regression analysis was performed to estimate the risk and severity of prematurity in relation to parity among mothers with previous GDM, current GDM, and recurrent GDM (previous and current GDM), using mothers without GDM as the reference group. Z-test and ratio of odds ratios (ROR) were used to determine subgroup differences.

RESULTS

Maternal GDM increased the risk of preterm birth in both nullipara (OR_adj = 1.28, 95 %CI: 1.14-1.45) and multipara (OR_adj = 1.26, 95 %CI: 1.14-1.40). However, the risk of premature delivery in multiparous mothers with recurrent GDM and those with current GDM did not differ significantly, with a ROR of 0.89 (95 %CI: 0.71-1.12). The risk of recurrent GDM on preterm birth was most pronounced among multiparous mothers with pre-pregnancy BMI above 30 kg/m² (OR_adj = 2.18, 95 %CI: 1.25-3.82) as compared with those with current GDM alone (ROR = 2.20, 95 %CI: 1.07-4.52). The risk of GDM for moderate preterm birth was similar to that of overall preterm birth. In contrast, GDM was not associated with very preterm birth irrespective of parity (all P values > 0.05).

CONCLUSIONS

Maternal GDM increased the risk of preterm birth in nullipara and multipara, whereas recurrent GDM was not associated with a further increase in the risk of prematurity in multiparous mothers. Maternal GDM did not contribute to very preterm birth irrespective of parity. Our findings can be useful for facilitating more targeted preventive strategies for adverse pregnancy outcomes.

Differential effect of pre-pregnancy low BMI on fetal macrosomia: a population-based cohort study

BACKGROUND

The differential effect of pre-pregnancy low BMI on macrosomia has not been fully addressed. Herein, we conducted a city-wide population-based cohort study to illuminate the association between pre-pregnancy low BMI and macrosomia, stratifying by maternal age, parity, and GDM status.

METHODS

All pregnant women who paid their first prenatal visit to the hospital in Qingdao during August 1, 2018, to June 30, 2020, were recruited to this study. The interactive effect of maternal age and pre-pregnancy low BMI on macrosomia was evaluated using logistic regression models, followed by strata-specific analyses.

RESULTS

A total of 105,768 mother-child pairs were included, and the proportion of fetal macrosomia was 11.66%. The interactive effect of maternal pre-pregnancy BMI and age was statistically significant on macrosomia irrespective of parity (nullipara: P_adjusted=0.0265; multipara: P_adjusted=0.0356). The protective effect of low BMI on macrosomia was most prominent among nullipara aged 35 years and above (aOR=0.16, 95% CI 0.05-0.49) and multipara aged 25 years and below (aOR=0.17, 95% CI 0.05-0.55). In nullipara without GDM, the risk estimates gradually declined with increasing conception age (20-to-24 years: aOR=0.64, 95% CI 0.51-0.80; 25-to-29 years: aOR=0.43 95% CI 0.36-0.52; 30-to-34 years: aOR=0.40 95% CI 0.29-0.53; and ≥35 years: aOR=0.19, 95% CI 0.06-0.60). A similar pattern could also be observed in nullipara with GDM, where the aOR for low BMI on macrosomia decreased from 0.54 (95% CI 0.32-0.93) in pregnant women aged 25-29 years to 0.30 (95% CI 0.12-0.75) among those aged 30-34 years. However, younger multiparous mothers, especially those aged 25 years and below without GDM (aOR=0.21, 95% CI 0.06-0.68), were more benefited from a lower BMI against the development of macrosomia.

CONCLUSIONS

Maternal low BMI is inversely associated with macrosomia irrespective of maternal age and parity. The impact of pre-pregnancy low BMI on macrosomia varied by maternal age and parity. The protective effect of a lower maternal BMI against fetal macrosomia was more prominent in nulliparous mothers aged 35 years and above, whereas multiparous mothers younger than 25 years of age were more benefited.

Risk of recurrent preterm birth among women according to change in partner

There is well-established literature indicating change in partner as a risk for preeclampsia, yet the research on the risk of preterm birth after a change in partners has been sparse and inconsistent. Using a population of California live born singletons, we aimed to determine the risk of preterm birth after a change in partner between the first and second pregnancies. The risk of preterm and early term delivery in the second pregnancy was calculated for mothers who did or did not change partners between births with the referent group as women who delivered both pregnancies at term and did not change partners. Adjusted odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated. Relative to women who delivered at 39 weeks or later in the second pregnancy and did not change partners, preterm birth risks were somewhat lower for women who changed partners between the first and second pregnancies compared to those women who did not change partners. For example, 10.6% of women who did not change partners and delivered their second pregnancy before 34 weeks also delivered their first pregnancy before 34 weeks, while 8.5% of women who changed partners delivered before 34 weeks. Findings suggest partner change may alter the risk of preterm birth.

The association between parity and birthweight in a longitudinal consecutive pregnancy cohort

BACKGROUND

Nulliparity is associated with lower birthweight, but few studies have examined how within-mother changes in risk factors impact this association.

METHODS

We used longitudinal electronic medical record data from a hospital-based cohort of consecutive singleton live births from 2002-2010 in Utah. To reduce bias from unobserved pregnancies, primary analyses were limited to 9484 women who entered nulliparous from 2002-2004, with 23,380 pregnancies up to parity 3. Unrestricted secondary analyses used 101,225 pregnancies from 45,212 women with pregnancies up to parity 7. We calculated gestational age and sex-specific birthweight z-scores with nulliparas as the reference. Using linear mixed models, we estimated birthweight z-score by parity adjusting for pregnancy-specific sociodemographics, smoking, alcohol, prepregnancy body mass index, gestational weight gain, and medical conditions.

RESULTS

Compared with nulliparas', infants of primiparas were larger by 0.20 unadjusted z-score units [95% confidence interval (CI) 0.18, 0.22]; the adjusted increase was similar at 0.18 z-score units [95% CI 0.15, 0.20]. Birthweight continued to increase up to parity 3, but with a smaller difference (parity 3 vs. 0 β = 0.27 [95% CI 0.20, 0.34]). In the unrestricted secondary sample, there was significant departure in linearity from parity 1 to 7 (P < 0.001); birthweight increased only up to parity 4 (parity 4 vs. 0 β = 0.34 [95% CI 0.31, 0.37]).

CONCLUSIONS

The association between parity and birthweight was non-linear with the greatest increase observed between first- and second-born infants of the same mother. Adjustment for changes in weight or chronic diseases did not change the relationship between parity and birthweight.

Change in paternity and select perinatal outcomes: causal or confounded?

Select social, behavioural and maternal characteristics were evaluated to determine if they were confounding factors in the association between paternity change and pre-eclampsia, small for gestational age (SGA) and pre-term delivery, in a sample of 1,409 women. Multivariate logistic regression analysis was used to determine if any of these risk factors modified the association between changing paternity and the selected perinatal outcomes. Results of the analysis showed that women who changed partners were more likely to possess potentially confounding risk factors compared with those who had not. Paternity change was 2.75 times more likely to be associated with the development of pre-eclampsia (95% CI 1.33; 5.68) and 2.25 times more likely to be associated with an SGA infant on weight (95% CI 1.13; 4.47), after adjusting for selected risk factors. Paternity change remains a significant risk factor for pre-eclampsia and SGA in the presence of select risk factors.

The paternal role in pre-eclampsia and giving birth to a small for gestational age infant; a population-based cohort study

OBJECTIVE

To estimate the effect of partner change on risks of pre-eclampsia and giving birth to a small for gestational age infant.

DESIGN

Prospective population study.

SETTING

Sweden.

PARTICIPANTS

Women with their first and second successive singleton births in Sweden between 1990 and 2006 without pregestational diabetes and/or hypertension (n=446 459).

OUTCOME MEASURES

Preterm (<37 weeks) and term (≥37 weeks) pre-eclampsia, and giving birth to a small for gestational age (SGA) infant. Risks were adjusted for interpregnancy interval, maternal age, body mass index, height and smoking habits in second pregnancy, years of involuntary childlessness before second pregnancy, mother's country of birth, years of formal education and year of birth. Further, when we calculated risks of SGA we restricted the study population to women with non-pre-eclamptic pregnancies.

RESULTS

In women who had a preterm pre-eclampsia in first pregnancy, partner change was associated with a strong protective effect for preterm pre-eclampsia recurrence (OR 0.24; 95% CI 0.07 to 0.88). Similarly, partner change was also associated with a protective effect of recurrence of SGA birth (OR 0.75; 95% CI 0.67 to 0.84). In contrast, among women without SGA in first birth, partner change was associated with an increased risk of SGA in second pregnancy. Risks of term pre-eclampsia were not affected by partner change.

CONCLUSIONS

There is a paternal effect on risks of preterm pre-eclampsia and giving birth to an SGA infant.

U.S. Maternally linked birth records may be biased for Hispanics and other population groups

PURPOSE

We sought to advance understanding of linkage error in U.S. maternally linked datasets and how the error might affect results of studies based on the linked data.

METHODS

North Carolina birth and fetal death records for 1988-1997 were maternally linked (n=1,030,029). The maternal set probability, defined as the probability that all records assigned to the same maternal set do in fact represent events to the same woman, was used to assess differential maternal linkage error across race/ethnic groups.

RESULTS

Maternal set probabilities were lower for records specifying Asian or Hispanic race/ethnicity, suggesting greater maternal linkage error for these sets. The lower probabilities for Hispanics were concentrated in women of Mexican origin who were not born in the United States.

CONCLUSIONS

Differential linkage error may be a source of bias in studies that use U.S. maternally linked datasets to make comparisons between Hispanics and other groups or among Hispanic subgroups. Methods to quantify and adjust for this potential bias are needed.

Novel risk factor in gastroschisis: Change of paternity

In recent years, an increase in the rate of gastroschisis has been documented in several countries throughout the world. Based on accumulating evidence that a maternal immunologic response to a novel set of paternal antigens may be involved in risk for several adverse pregnancy outcomes, including preeclampsia, reduced birth weight, and preterm delivery, we tested the hypothesis that a pregnancy following a change in fathers (change in paternity) may be a risk factor for gastroschisis. Using a case-control design, we compared the prevalence of change in paternity with the index pregnancy in 102 mothers of isolated gastroschisis cases to the prevalence of change in paternity in 117 mothers of non-malformed infants and 78 mothers of infants with neural tube defects or oral clefts. In a multivariate analysis, the adjusted odds of change in paternity in multigravid case mothers were 7.81 times higher (95% Confidence interval 2.80-21.88) relative to multigravid mothers of malformed and non-malformed controls combined, after adjustment for maternal age. These data suggest that maternal immune factors may play a role in the cause of gastroschisis. Further research is needed to corroborate these findings and to elucidate possible immunologic mechanisms involved in the pathogenesis of gastroschisis.

A new method for measuring misclassification of maternal sets in maternally linked birth records: true and false linkage proportions

OBJECTIVES

Numerous studies have used maternally linked birth records to investigate perinatal outcomes, maternal behaviors, and the quality of vital records birth data. Little attention has been given to assessing errors in the linkages and to understanding how such errors affect estimates derived from the linked data. The author developed a framework for conceptualizing maternal linkage error and measures for quantifying it, and examined the behavior of the new measures in a maternally linked file.

METHODS

Linkage errors were conceptualized as misclassification, with the classes being the maternal sets (records classified as representing different births to the same woman). The true linkage proportion, analogous to sensitivity, was used to capture the degree to which all of a woman's births were assigned to a single maternal set; the false linkage proportion, analogous to specificity, was used to capture the degree to which the assigned maternal sets combined births from different women. The behavior of the two proportions was examined by introducing increasing degrees of linkage error into a maternally linked file.

RESULTS

Both measures indicated greater misclassification with increasing simulated linkage errors.

CONCLUSIONS

The new measures may be a useful tool for assessing the quality of maternally linked data, as well as other types of linked records where the linkages are within a single file. This is a necessary step towards developing methods for addressing misclassification bias in studies of maternally linked records through sensitivity analysis, adjustment, and other means.

[Genes and intra-uterine growth retardation]

Genetic analysis of growth from birth to adulthood shows the existence of a strong genetic component in the variance of size at particular milestones in the growth process, such as height at take-off, at peak velocity and at adulthood. While it is well known that postnatal growth is strongly genetically determined, the importance of genes in normal variations of prenatal growth is less known. Genetic analysis of prenatal growth in human is not an easy problem and weighing the genetic and non-genetic component in intra-uterine growth retardation an almost impossible task. It is now well known that adults who had a low birthweight or who were thin at birth, with a low ponderal index, tend to be insulin resistant and have an increased risk of developing non-insulin-dependent diabetes mellitus later in life. According to the thrifty genotype hypothesis, genes predisposing to type 2 diabetes mellitus are very likely to have been survival genes for our ancestors, helping them to store energy during long periods of starvation. Both epidemiological surveys of adults born after prenatal exposure to exposure to famine and biochemical investigations of insulin resistance in low birthweight children show that the association between a low birthweight and an increased risk of developing type 2 diabetes mellitus later in life has a genetic basis. While low birthweight infants have a decreased survival probability in infancy, having a small baby may have been a selective advantage during long periods of starvation. This could explain why the same genetic variants cause low birthweight phenotype and insulin resistance predisposing to non-insulin-dependent diabetes.