High Parity and Fetal Morbidity Outcomes

Correlates of fertility desires in women with urogenital fistula in the Democratic Republic of Congo: a cross-sectional study of 1,646 women

BACKGROUND

Studies on fertility desires among fistula patients in the Democratic Republic of Congo (DRC) have been conducted on fewer patients. Furthermore, these studies have adopted a univariate descriptive approach. This study aims to examine the determinants of fertility desires among patients with fistula in the DRC.

METHODS

This cross-sectional study included women aged 15-49 whose fistulas were repaired by the Panzi Hospital mobile team in seven DRC regions between 2013 and 2018. Univariate and bivariate descriptive analyses were performed using the frequency distribution table and the chi-square test. Adjusted odds ratios with their 95 confidence intervals from logistic regression were used to analyze factors associated with fertility desire after fistula repair. All analyses were stratified by parity level for all women aged 15-49 and 20-34 years.

RESULTS

Of the 1,646 women aged 15-49 and 808 aged 20-34, 948 (57.6%) and 597 (73.8%), respectively, wanted to have children after fistula repair. Among women aged 15-49 and 20-34 years, the desire to have children was parity-specific. It was negatively associated with age at all parity levels. In women with low parity, the desire for children was significantly negatively associated with a high number of surgeries, abortions, and fistula duration. It tended to decrease with time, but was particularly high in 2014 and 2017. It was high among the Protestant women. Among medium-parity women, it was significantly lower in urban areas and among widows, but higher among women who had more than two abortions. Among high-parity women, it was negatively associated with education level.

CONCLUSION

To help women with fistula achieve or approach their desired number of children, our findings suggest that (1) counseling is needed for women with a high desire for children; (2) the human, material, and financial resources needed to eliminate fistula in the DRC should be made available; and (3) medical and nursing staff should be sufficiently and effectively trained to minimize the number of unsuccessful surgeries performed on women with fistula.

Poultry Concentrated Animal-Feeding Operations on the Eastern Shore, Virginia, and Geospatial Associations with Adverse Birth Outcomes

Concentrated animal-feeding operations (CAFOs) emit pollution into surrounding areas, and previous research has found associations with poor health outcomes. The objective of this study was to investigate if home proximity to poultry CAFOs during pregnancy is associated with adverse birth outcomes, including preterm birth (PTB) and low birth weight (LBW). This study includes births occurring on the Eastern Shore, Virginia, from 2002 to 2015 (N = 5768). A buffer model considering CAFOs within 1 km, 2 km, and 5 km of the maternal residence and an inverse distance weighted (IDW) approach were used to estimate proximity to CAFOs. Associations between proximity to poultry CAFOs and adverse birth outcomes were determined by using regression models, adjusting for available covariates. We found a −52.8 g (−95.8, −9.8) change in birthweight and a −1.51 (−2.78, −0.25) change in gestational days for the highest tertile of inverse distance to CAFOs. Infants born with a maternal residence with at least one CAFO within a 5 km buffer weighed −47 g (−94.1, −1.7) less than infants with no CAFOs within a 5 km buffer of the maternal address. More specific measures of exposure pathways via air and water should be used in future studies to refine mediators of the association found in the present study.

Uterine Transplantation: Review of Livebirths and Reproductive Implications

Uterine transplantation (UTx) is a fertility restoring treatment for women with absolute uterine factor infertility. At a time when there is no question of the procedure's feasibility, and as the number of livebirths begins to increase exponentially, various important reproductive, fetal, and maternal medicine implications have emerged. Detailed outcomes from 17 livebirths following UTx are now available, which are reviewed herein, along with contextualized extrapolation from pregnancy outcomes in other solid organ transplants. Differences in recipient demographics and reproductive aspirations between UTx and other transplant recipients make extrapolating management strategies and outcomes in other solid organ transplants inappropriate. Whereas preterm delivery remains prominent, small for gestational age or hypertensive disorders do not appear to be as prevalent following UTx when compared to other solid organ transplants. Given the primary objective of undertaking UTx is to achieve a livebirth, publication of reproductive outcomes is essential at this early stage, to reflect on and optimize the management of future cases.

Maternal proximity to Central Appalachia surface mining and birth outcomes

Supplemental Digital Content is available in the text.

Maternal residency in Central Appalachia counties with coal production has been previously associated with increased rates of low birth weight (LBW). To refine the relationship between surface mining and birth outcomes, this study employs finer spatiotemporal estimates of exposure.

Maternal veterinary occupation and adverse birth outcomes in Washington State, 1992-2014: a population-based retrospective cohort study

OBJECTIVE

Women in veterinary occupations are routinely exposed to potential reproductive hazards, yet research into their birth outcomes is limited. We conducted a population-based retrospective cohort study of the association between maternal veterinary occupation and adverse birth outcomes.

METHODS

Using Washington State birth certificate, fetal death certificate and hospital discharge data from 1992 to 2014, we compared birth outcomes of mothers in veterinary professions (n=2662) with those in mothers in dental professions (n=10 653) and other employed mothers (n=8082). Relative risks (RRs) and 95% CIs were estimated using log binomial regression. Outcomes studied were premature birth (<37 weeks), small for gestational age (SGA), malformations and fetal death (death at ≥20 weeks gestation). Subgroup analyses evaluated risk of these outcomes among veterinarians and veterinary support staff separately.

RESULTS

While no statistically significant associations were found, we noted a trend for SGA births in all veterinary mothers compared with dental mothers (RR=1.16, 95% CI 0.99 to 1.36) and in veterinarians compared with other employed mothers (RR=1.37, 95% CI 0.96 to 1.96). Positive but non-significant association was found for malformations among children of veterinary support staff.

CONCLUSIONS

These results support the need for further study of the association between veterinary occupation and adverse birth outcomes.

The effect of parity on maternal body mass index, plasma mineral element status and new-born anthropometrics

BACKGROUND

Adverse pregnancy outcome is an important public health problem that has been partly associated with increasing maternal parity.

AIM

To determine the effect of parity on maternal body mass index (BMI), mineral element status and newborn anthropometrics.

METHODS

Data for 349 pregnant women previously studied for the impacts of maternal plasma mineral element status on pregnancy and its outcomes was analysed. Obstetric and demographic data and 5mls of blood samples were obtained from each subject. Blood lead, plasma copper, iron and zinc were determined using atomic absorption spectrophotometer.

RESULTS

Maternal BMI increases with parity. Women with parity two had significantly higher plasma zinc but lower plasma copper with comparable levels of the elements in nulliparous and higher parity groups. Although plasma iron was comparable among the groups, blood lead was significantly higher in parity > three. Newborn birth length increases with parity with a positive correlation between parity and maternal BMI (r = 0.221; p = 0.001) and newborn birth length (r = 0.170; p = 0.002) while plasma copper was negatively correlated with newborn's head circumference (r = -0.115; p = 0.040).

CONCLUSION

It is plausible that parity affects maternal BMI and newborn anthropometrics through alterations in maternal plasma mineral element levels. While further studies are desired to confirm the present findings, there is need for pregnant and would-be pregnant women to diversify their diet to optimize their mineral element status.

Maternal Grand Multiparity and the Risk of Severe Mental Disorders in Adult Offspring

BACKGROUND

Previous studies have shown that maternal grand multiparity may predict an increased risk of mental disorders in young adult offspring, but whether such effects persist throughout adulthood remains unknown. The current study examined if maternal grand multiparity predicts the risks of severe mental disorders, suicides, suicide attempts and dementias throughout adult life.

METHODS

Our study sample comprised 13243 Helsinki Birth Cohort Study 1934-1944 participants (6905 men and 6338 women). According to hospital birth records, 341 offspring were born to grand multiparous mothers. From Finnish national hospital discharge and causes of death registers, we identified 1682 participants diagnosed with mental disorders during 1969-2010.

RESULTS

Maternal grand multiparity predicted significantly increased risks of mood disorders (Hazard Ratio = 1.64, p = 0.03), non-psychotic mood disorders (Hazard Ratio = 2.02, p = 0.002), and suicide attempts (Hazard Ratio = 3.94, p = 0.01) in adult offspring. Furthermore, women born to grand multiparous mothers had significantly increased risks of any severe mental disorder (Hazard Ratio = 1.79, p = 0.01), non-psychotic substance use disorders (Hazard Ratio = 2.77, p = 0.02) schizophrenia, schizotypal and delusional disorders (Hazard Ratio = 2.40, p = 0.02), mood disorders (Hazard Ratio = 2.40, p = 0.002), non-psychotic mood disorders (Hazard Ratio = 2.91, p<0.001), and suicide attempts (Hazard Ratio = 5.05, p = 0.01) in adulthood. The effects of maternal grand multiparity on offspring psychopathology risk were independent of maternal age and body mass index at childbirth, and of year of birth, sex, childhood socioeconomic position, and birth weight of the offspring. In contrast, no significant effects were found among men.

CONCLUSIONS

Women born to grand multiparous mothers are at an increased risk of severe mental disorders and suicide attempts across adulthood. Our findings may inform the development of preventive interventions for mental disorders.

Pregnancy outcomes and birth defects from an antiretroviral drug safety study of women in South Africa and Zambia

OBJECTIVE

To evaluate the safety of combination antiretroviral therapy (ART) in conception and pregnancy in different health systems.

DESIGN

A pilot ART registry to measure the prevalence of birth defects and adverse pregnancy outcomes in South Africa and Zambia.

METHODS

HIV-infected pregnant women on ART prior to conception were enrolled until delivery, and their infants were followed until 1 year old.

RESULTS

Between October 2010 and April 2011, 600 women were enrolled. The median CD4 cell count at study enrollment was lower in South Africa than Zambia (320 vs. 430 cells/μl; P < 0.01). The most common antiretroviral drugs at the time of conception included stavudine, lamivudine, and nevirapine. There were 16 abortions (2.7%), one ectopic pregnancy (0.2%), 12 (2.0%) stillbirths, and 571 (95.2%) live infants. Deliveries were more often preterm (29.7 vs. 18.4%; P = 0.01) and the infants had lower birth weights (2900 vs. 2995 g; P = 0.11) in Zambia compared to South Africa. Thirty-six infants had birth defects: 13 major and 23 minor. There were more major anomalies detected in South Africa and more minor ones in Zambia. No neonatal deaths were attributed to congenital birth defects.

CONCLUSIONS

An Africa-specific, multi-site antiretroviral drug safety registry for pregnant women is feasible. Different prevalence for preterm delivery, delivery mode, and birth defect types between women on preconception ART in South Africa and Zambia highlight the potential impact of health systems on pregnancy outcomes. As countries establish ART drug safety registries, documenting health facility limitations may be as essential as the specific ART details.

Perinatal factors and the risk of bipolar disorder in Finland

BACKGROUND

Complications during the perinatal period have been associated with neurodevelopmental disorders like schizophrenia and autism. However, similar studies on bipolar disorder (BPD) have been limited and the findings are inconsistent. The aim of this study was to examine the association between perinatal risk factors and BPD.

METHODS

This nested case-control study, based on the Finnish Prenatal Study of Bipolar Disorders (FIPS-B), identified 724 cases and 1419 matched controls from population based registers. Conditional logistic regression was used to examine the associations between perinatal factors and BPD adjusting for potential confounding due to maternal age, psychiatric history and educational level, place of birth, number of previous births and maternal smoking during pregnancy.

RESULTS

Children delivered by planned cesarean section had a 2.5-fold increased risk of BPD (95% CI: 1.32-4.78, P<0.01). No association was seen between other examined perinatal risk factors and BPD.

LIMITATIONS

The limitations of this study include: the restriction in the sample to treated cases of BPD in the population, and usage of hospital based clinical diagnosis for case ascertainment. In addition, in spite of the large sample size, there was low power to detect associations for certain exposures including the lowest birth weight category and pre-term birth.

CONCLUSIONS

Birth by planned cesarean section was associated with risk of BPD, but most other perinatal risk factors examined in this study were not associated with BPD. Larger studies with greater statistical power to detect less common exposures and studies utilizing prospective biomarker-based exposures are necessary in the future.

Obstetric risk factors and autism spectrum disorders in Finland

OBJECTIVE

To examine the relationship between obstetric risk factors and childhood autism, Asperger syndrome, and other pervasive developmental disorders (PDDs).

STUDY DESIGN

Registry-based case-control study from all singleton births in Finland from 1990-2005. Cases with childhood autism, Asperger syndrome, or PDD (n = 4713) were identified from the Finnish Hospital Discharge Register. Each case was matched to 4 controls on sex, date of birth, and place of birth. Information on obstetric risk factors was from the Finnish Medical Birth Register. Conditional logistic regression models were used for statistical analyses.

RESULTS

When adjusted with confounders, childhood autism was associated with maternal high blood pressure (OR 1.49, 95% CI 1.1-2.1, P = .018), Apgar scores less than 7 (1 minute, OR 1.46, 95% CI 1.1-2.0, P = .021), and neonatal treatment with monitoring (OR 1.40, 95% CI 1.02-1.9, P = .038). PDD was associated with induced labor (OR 1.25 95% CI 1.1-1.5, P = .007), planned cesarean delivery (OR 1.34, 95% CI 1.1-1.7, P = .009), 1-minute Apgar scores 7-8 ( OR 1.22, 95% CI 1.1-1.4, P = .008) and less than 7 (OR 1.34, 95% CI 1.03-1.8, P = .032), and neonatal intensive care unit treatment (OR 1.52, 95% CI 1.2-2.0, P = .003). Asperger syndrome was associated only with 1-minute Apgar scores 7-8 (OR 1.19, 95% CI 1.03-1.4, P = .018).

CONCLUSIONS

Low Apgar scores as well as conditions requiring neonatal special follow-up are important risk factors for childhood autism and PDD. These findings suggest that fetal distress is a potential risk factor for these disorders, but not for Asperger syndrome.

Grand multiparity: is it still a risk in pregnancy?

Background

The association of grand multiparity and poor pregnancy outcome has not been consistent for decades. Classifying grand multiparous women as a high-risk group without clear evidence of a consistent association with adverse outcomes can lead to socioeconomic burdens to the mother, family and health systems. We compared the maternal and perinatal complications among grand multiparous and other multiparous women in Dar es Salaam in Tanzania.

Methods

A cross-sectional study was undertaken at Muhimbili National Hospital (MNH). A standard questionnaire enquired the following variables: demographic characteristics, antenatal profile and detected obstetric risk factors as well as maternal and neonatal risk factors. Predictors of adverse outcomes in relation to grand multiparous women were assessed at p = 0.05.

Results

Grand multiparas had twice the likelihood of malpresentation and a threefold higher prevalence of meconium-stained liquor and placenta previa compared with lower-parity women even when adjusted for age. Neonates delivered by grand multiparous women (12.1%) were at three-time greater risk of a low Apgar score compared with lower-parity women (5.4%) (odds ratio (OR), 2.9; 95% confidence interval (CI), 1.5–5.0). Grand multiparity and low birth weight were independently associated with a low Apgar score (OR, 2.4; 95%, CI 1.4–4.2 for GM; OR, 4.2; 95% CI, 2.3–7.8) for low birth weight.

Conclusion

Grand multiparity remains a risk in pregnancy and is associated with an increased prevalence of maternal and neonatal complications (malpresentation, meconium-stained liquor, placenta previa and a low Apgar score) compared with other multiparous women who delivered at Muhimbili National Hospital.

Is Gravidity 4+ a Risk Factor for Oral Clefts? A Case-Control Study in Eight South American Countries Using Structural Equation Modeling

Background

There is disagreement about the association between cleft lip with or without cleft palate and multigravidity, which could be explained by differences of adjusting for maternal age, Amerindian ancestry, and socioeconomic status.

Objective

The aim was to evaluate gravidity 4+ (four or more gestations) as a risk factor for cleft lip with or without cleft palate in South America.

Design

We used a matched (1:1) case-control study with structural equation modeling for related causes. Data were obtained from 1,371,575 consecutive newborn infants weighing ≥500 g who were born in the hospitals of the Estudio Colaborativo Latinoamericano de Malformaciones Congénitas (ECLAMC) network between 1982 and 1999. There were a total of 1,271 cases with cleft lip with or without cleft palate (excluding midline and atypical cleft lip with or without cleft palate). A total of 1,227 case-control pairs were obtained, matched by maternal age, newborn gender, and year and place of birth. Potential confounders and intermediary variables were analyzed with structural equation modeling.

Results

The crude risk of gravidity 4+ was 1.41 and the 95% confidence interval was 1.14 to 1.61. When applying structural equation modeling, the effect of multigravidity on the risk of cleft lip with or without cleft palate was 1.22 and the 95% confidence interval was 0.91 to 1.39.

Conclusions

Multigravid mothers (more than four gestations) showed no greater risk of bearing children who had cleft lip with or without cleft palate than mothers with two or three births. Therefore, the often observed and reported association between multigravidity and oral clefts likely reflects the effect of other risk factors related to low socioeconomic status in South American populations.

Risk of autism spectrum disorders in low birth weight and small for gestational age infants

OBJECTIVE

To examine the relationship between birth weight, gestational age, small for gestational age (SGA), and 3 of the most common autism spectrum disorder (ASD) subtypes.

STUDY DESIGN

In this population-based case-control study conducted in Finland, 4713 cases born between 1987 and 2005 with International Classification of Diseases-diagnoses of childhood autism, Asperger syndrome, or pervasive developmental disorder (PDD), were ascertained from the Finnish Hospital Discharge Register. Four controls, individually matched on sex, date of birth, and place of birth, were selected from the Finnish Medical Birth Register for each case. Conditional logistic regression models were used to assess whether birth weight and gestational age information predicted ASD after controlling for maternal age, parity, smoking during pregnancy, and psychiatric history, as well as for infant's major congenital anomalies.

RESULTS

Very low (<1500 g) and moderately low (<2500 g) birth weight, very low gestational age (less than 32 weeks), and SGA increased risk of childhood autism (adjusted OR 3.05, 95% CI 1.4-6.5; 1.57, 1.1-2.3; 2.51, 1.3-5.0; and 1.72, 1.1-2.6, respectively). Very low and moderately low birth weight, very low gestational age, and SGA were also associated with increase in PDD risk (OR 3.44, 95% CI 1.9-6.3; 1.81, 1.4-2.4; 2.46, 1.4-2.3; and 2.24, 1.7-3.0, respectively). No associations were found between the perinatal characteristics and Asperger syndrome. The increased risks persisted after controlling for selected potential confounders.

CONCLUSIONS

The finding that low birth weight, prematurity, and SGA were related to childhood autism and PDD but not to Asperger syndrome suggests that prenatal factors related to these exposures may differ for these ASD subtypes, which may have preventive implications.

Effect of high parity on occurrence of some fetal growth indices: a cohort study

The objective of this retrospective cohort study was to explore the potential causal relation between parity and fetal growth indices, including low birth weight (LBW), macrosomia, and prematurity. The study was nested on a community trial in a city in Oman. The study analyzed 1939 pregnancies among 479 participants. Of these, 944 pregnancies (48.7%) were high parity (≥5). Obtained newborns with outcomes of interest were as follows: 191 LBW, 34 macrosomic, and 69 premature. Associations were measured using multilevel logistic regression modeling. Compared to low parity (LP, defined as <5), high parity was found to be associated with less risk of LBW (relative risk [RR] = 0.76; 95% confidence interval [CI]: 0.44–1.1) and prematurity (RR = 0.82; 95% CI: 0.54–1.27), but greater risk of macrosomia (RR = 1.8; 95% CI: 1.2–2.4). This study provides evidence that with increasing parity, risks of LBW and prematurity decrease, while risk of macrosomia increases.

Maternal and neonatal outcomes of grand multiparas over two decades in Mali

OBJECTIVE

To analyze the association between grand multiparity and maternal and neonatal morbidity and mortality.

DESIGN

Retrospective cross-sectional study.

SETTING

Point G National Hospital, a tertiary care hospital in Bamako, Mali.

POPULATION

All singleton births from 1985 to 2003.

METHODS

Cross-sectional study of 13 340 singleton births at a tertiary care hospital in Mali (1985-2003) compared outcomes between 3617 grand multiparas (para ≥5) and 9723 pauciparas (para 1-4). Odds ratios (OR) were adjusted for maternal age, prenatal care utilization, socioeconomic status, and region of origin.

MAIN OUTCOME MEASURES

Maternal mortality, perinatal mortality, placental abnormalities (previa and abruption), uterine rupture, postpartum infection, postpartum hemorrhage, eclampsia, cesarean delivery, mean birthweight, low birthweight, high birthweight.

RESULTS

Grand multiparas were older, poorer, and less likely to have accessed prenatal care. Grand multiparas had a lower adjusted odds of maternal death (adjusted OR, 0.66; 95%CI, 0.45-0.97), but higher adjusted odds of perinatal death (adjusted OR, 1.33; 95%CI, 1.12-1.59), placental abnormalities (adjusted OR, 1.57; 95%CI, 1.21-2.05), and high birthweight (adjusted OR, 1.42; 95%CI, 1.05-1.92).

CONCLUSIONS

The healthy person effect may explain grand multiparas' lower odds of maternal death. Reducing grand multiparity and improving grand multiparas' access to prenatal care may improve population-level perinatal outcomes.

The association between parity, infant gender, higher level of paternal education and preterm birth in Pakistan: a cohort study

BACKGROUND

High rates of antenatal depression and preterm birth have been reported in Pakistan. Self reported maternal stress and depression have been associated with preterm birth; however findings are inconsistent. Cortisol is a biological marker of stress and depression, and its measurement may assist in understanding the influence of self reported maternal stress and depression on preterm birth.

METHODS

In a prospective cohort study pregnant women between 28 to 30 weeks of gestation from the Aga Khan Hospital for Women and Children completed the A-Z Stress Scale and the Centre for Epidemiology Studies Depression Scale to assess stress and depression respectively, and had a blood cortisol level drawn. Women were followed up after delivery to determine birth outcomes. Correlation coefficients and Wilcoxon rank sum test was used to assess relationship between preterm birth, stress, depression and cortisol. Logistic regression analysis was used to determine the key factors predictive of preterm birth.

RESULTS

132 pregnant women participated of whom 125 pregnant women had both questionnaire and cortisol level data and an additional seven had questionnaire data only. Almost 20% of pregnant women (19·7%, 95% CI 13·3-27·5) experienced a high level of stress and nearly twice as many (40·9%, 95% CI 32·4-49·8%) experienced depressive symptoms. The median of cortisol level was 27·40 ug/dl (IQR 22·5-34·2). The preterm birth rate was 11·4% (95% CI 6·5-18). There was no relationship between cortisol values and stress scale or depression. There was a significant positive relationship between maternal depression and stress. Preterm birth was associated with higher parity, past delivery of a male infant, and higher levels of paternal education. Insufficient numbers of preterm births were available to warrant the development of a multivariable logistic regression model.

CONCLUSIONS

Preterm birth was associated with higher parity, past delivery of a male infant, and higher levels of paternal education. There was no relationship between stress, and depression, cortisol and preterm birth. There were high rates of stress and depression among this sample suggesting that there are missed opportunities to address mental health needs in the prenatal period. Improved methods of measurement are required to better understand the psychobiological basis of preterm birth.

The association between high parity and obesity in women living in South-eastern Turkey

BACKGROUND AND AIM

One of the major public health problems in Turkey is the high prevalence of obesity, which is particularly frequent among women. As it has been reported that parity affects body fat and BMI, the aim of this study was to evaluate the association between parity number, socioeconomic status and obesity.

SUBJECTS AND METHODS

The study involved 286 married or divorced women aged 28- 80 years (mean age: 46.7+/-9.7), who were divided into two groups depending on whether they had experienced three or fewer pregnancies (group 1) or four or more pregnancies (group 2). We measured their body weight and height, and waist and hip circumferences, calculated their BMI, and determined their body fat percentage and fat mass by means of bioelectric impedance.

RESULTS

The women in group 2 had a higher BMI, a greater fat percentage and fat mass, a larger waist circumference and higher waist/hip ratio values than those in group 1, and their mean age and illiteracy ratio were also higher. There was a significant correlation between parity number and body weight, BMI and hip circumference.

CONCLUSIONS

Among other risk factors, a high parity number and socioeconomic indices may be associated with obesity in women.

Early childhood origins of the income/health gradient: The role of maternal health behaviors

Several recent studies in the US, Canada, and the UK have demonstrated a positive relationship between family income and child health, though the mechanisms underlying this relationship are poorly understood. Using data from the 1988 US National Maternal and Infant Health Survey and the 1991 follow-up, this paper tests whether maternal health status and health behaviors during pregnancy and early infancy can explain the relationship between family income and subjective health status at age 3. We find that, while a detailed set of controls for health risk factors including maternal smoking, drinking, and vitamin use during pregnancy, as well as breastfeeding and secondhand smoke exposure after birth, are significantly related to family income and maternal education, they do not explain the relationship between family income and maternal-assessed health of the child. We suggest that these results point to either more salient pathways through which family income impacts child health, such as maternal stress, or to the possibility that differences in subjective health status do not correspond to differences in objective health status in the same way for higher- and lower-income respondents.