Risk of Preterm Birth According to Maternal and Paternal Country of Birth: A Population-Based Study

Adverse Pregnancy Outcomes and International Immigration Status: A Systematic Review and Meta-analysis

Background:

Disparities in health outcomes between immigrant and native-origin populations, particularly pregnant women, pose significant challenges to healthcare systems. The aim of this systematic-review and meta-analysis was to investigate the risk of adverse pregnancy outcomes among immigrant-women compared to native-origin women in the host country.

Methods:

PubMed (including MEDLINE), Scopus, and Web of Science were searched to retrieve studies published in English language up to September 2020. All observational studies examining the prevalence of at least one of the short-term single pregnancy outcomes for immigrants who crossed international borders compared to native-origin pregnant population were included. The meta-prop method was used for the pooled-estimation of adverse pregnancy-outcomes’ prevalence. For pool-effect estimates, the association between the immigration-status and outcomes of interest, the random-effects model was applied using the model described by DerSimonian and Laird. I² statistic was used to assess heterogeneity. The publication bias was assessed using the Harbord-test. Meta-regression was performed to explore the effect of geographical region as the heterogeneity source.

Findings:

This review involved 11 320 674 pregnant women with an immigration-background and 56 102 698 pregnant women as the native-origin population. The risk of emergency cesarean section (Pooled-OR = 1.1, 95%CI = 1.0–1.2), shoulder dystocia (Pooled-OR = 1.1, 95%CI = 1.0–1.3), gestational diabetes mellites (Pooled-OR = 1.4, 95%CI = 1.2–1.6), small for gestational age (Pooled-OR=1.3, 95%CI = 1.1–0.4), 5-min Apgar less than 7 (Pooled-OR = 1.2, 95%CI = 1.0–1.3) and oligohydramnios (Pooled-OR = 1.8, 95%CI = 1.0–3.3) in the immigrant women were significantly higher than those with the native origin background. The immigrant women had a lower risk of labor induction (Pooled-OR = 0.8, 95%CI = 0.7–0.8), pregnancy induced hypertension (Pooled-OR = 0.6, 95%CI = 0.5–0.7) preeclampsia (Pooled-OR = 0.7, 95%CI = 0.6–0.8), macrosomia (Pooled-OR = 0.8, 95%CI = 0.7–0.9) and large for gestational age (Pooled-OR = 0.8, 95%CI = 0.7–0.8). Also, the risk of total and primary cesarean section, instrumental-delivery, preterm-birth, and birth-trauma were similar in both groups. According to meta-regression analyses, the reported ORs were not influenced by the country of origin.

Conclusion:

The relationship between the immigration status and adverse perinatal outcomes indicated a heterogenous pattern, but the immigrant women were at an increased risk of some important adverse pregnancy outcomes. Population-based studies with a focus on the various aspects of this phenomena are required to explain the source of these heterogenicities.

Perinatal and Neonatal Outcomes in Immigrants From Conflict-Zone Countries: A Systematic Review and Meta-Analysis of Observational Studies

Objectives

There are controversies regarding the risk of adverse pregnancy outcomes among immigrants from conflict-zone countries. This systematic review and meta-analysis aimed to investigate the risk of perinatal and neonatal outcomes among immigrants from conflict-zone countries compared to native-origin women in host countries.

Methods

A systematic search on the databases of PubMed/MEDLINE, Scopus, and Web of Science was carried out to retrieve studies on perinatal and neonatal outcomes among immigrants from Somalia, Iraq, Afghanistan, Yemen, Syria, Nigeria, Sudan, Ethiopia, Eritrea, Kosovo, Ukraine, and Pakistan. Only peer-reviewed articles published in the English language were included in the data analysis and research synthesis. The odds ratio and forest plots were constructed for assessing the outcomes of interests using the DerSimonian and Laird, and the inverse variance methods. The random-effects model and the Harbord test were used to account for heterogeneity between studies and assess publication bias, respectively. Further sensitivity analysis helped with the verification of the reliability and stability of our review results.

Results

The search process led to the identification of 40 eligible studies involving 215,718 pregnant women, with an immigration background from the conflict zone, and 12,806,469 women of native origin. The adverse neonatal outcomes of the risk of small for gestational age (Pooled OR = 1.8, 95% CI = 1.6, 2.1), a 5-min Apgar score <7 (Pooled OR = 1.4, 95% CI = 1.0, 2.1), stillbirth (Pooled OR = 1.9, 95% CI = 1.2, 3.0), and perinatal mortality (Pooled OR = 2, 95% CI = 1.6, 2.5) were significantly higher in the immigrant women compared to the women of native-origin. The risk of maternal outcomes, including the cesarean section (C-S) and emergency C-S, instrumental delivery, preeclampsia, and gestational diabetes was similar in both groups.

Conclusion

Although the risk of some adverse maternal outcomes was comparable in the groups, the immigrant women from conflict-zone countries had a higher risk of neonatal mortality and morbidity, including SGA, a 5-min Apgar score <7, stillbirth, and perinatal mortality compared to the native-origin population. Our review results show the need for the optimization of health care and further investigation of long-term adverse pregnancy outcomes among immigrant women.

Paternal country of origin and adverse neonatal outcomes in births to foreign-born women in Norway: A population-based cohort study

BACKGROUND

Migration is a risk factor for adverse neonatal outcomes. The various impacts of maternal origin have been reported previously. The aim of this study was to investigate associations between paternal origin and adverse neonatal outcomes in births to migrant and Norwegian-born women in Norway.

METHODS AND FINDINGS

This nationwide population-based study included births to migrant (n = 240,759, mean age 29.6 years [±5.3 SD]) and Norwegian-born women (n = 1,232,327, mean age 29.0 years [±5.1 SD]) giving birth in Norway in 1990-2016. The main exposure was paternal origin (Norwegian-born, foreign-born, or unregistered). Neonatal outcomes were very preterm birth (22+0-31+6 gestational weeks), moderately preterm birth (32+0-36+6 gestational weeks), small for gestational age (SGA), low Apgar score (<7 at 5 minutes), and stillbirth. Associations were investigated in migrant and Norwegian-born women separately using multiple logistic regression and reported as adjusted odds ratios (aORs) with 95% confidence intervals (CIs), adjusted for year of birth, parity, maternal and paternal age, marital status, maternal education, and mother's gross income. In births to migrant women, a foreign-born father was associated with increased odds of very preterm birth (1.1% versus 0.9%, aOR 1.20; CI 1.08-1.33, p = 0.001), SGA (13.4% versus 9.5%, aOR 1.48; CI 1.43-1.53, p < 0.001), low Apgar score (1.7% versus 1.5%, aOR 1.14; CI 1.05-1.23, p = 0.001), and stillbirth (0.5% versus 0.3%, aOR 1.26; CI 1.08-1.48, p = 0.004) compared with a Norwegian-born father. In Norwegian-born women, a foreign-born father was associated with increased odds of SGA (9.3% versus 8.1%, aOR 1.13; CI 1.09-1.16, p < 0.001) and decreased odds of moderately preterm birth (4.3% versus 4.4%, aOR 0.95; CI 0.91-0.99, p = 0.015) when compared with a Norwegian-born father. In migrant women, unregistered paternal origin was associated with increased odds of very preterm birth (2.2% versus 0.9%, aOR 2.29; CI 1.97-2.66, p < 0.001), moderately preterm birth (5.6% versus 4.7%, aOR 1.15; CI 1.06-1.25, p = 0.001), SGA (13.0% versus 9.5%, aOR 1.50; CI 1.42-1.58, p < 0.001), low Apgar score (3.4% versus 1.5%, aOR 2.23; CI 1.99-2.50, p < 0.001), and stillbirth (1.5% versus 0.3%, aOR 4.87; CI 3.98-5.96, p < 0.001) compared with a Norwegian-born father. In Norwegian-born women, unregistered paternal origin was associated with increased odds of very preterm birth (4.6% versus 1.0%, aOR 4.39; CI 4.05-4.76, p < 0.001), moderately preterm birth (7.8% versus 4.4%, aOR 1.62; CI 1.53-1.71, p < 0.001), SGA (11.4% versus 8.1%, aOR 1.30; CI 1.24-1.36, p < 0.001), low Apgar score (4.6% versus 1.3%, aOR 3.51; CI 3.26-3.78, p < 0.001), and stillbirth (3.2% versus 0.4%, aOR 9.00; CI 8.15-9.93, p < 0.001) compared with births with a Norwegian-born father. The main limitations of this study were the restricted access to paternal demographics and inability to account for all lifestyle factors.

CONCLUSION

We found that a foreign-born father was associated with adverse neonatal outcomes among births to migrant women, but to a lesser degree among births to nonmigrant women, when compared with a Norwegian-born father. Unregistered paternal origin was associated with higher odds of adverse neonatal outcomes in births to both migrant and nonmigrant women when compared with Norwegian-born fathers. Increased attention to paternal origin may help identify women in maternity care at risk for adverse neonatal outcomes.

The risk of small for gestational age in very low birth weight infants born to Asian or Pacific Islander mothers in California

OBJECTIVE

To evaluate potential differences and to show the risk associated with small for gestational age (SGA) at birth and discharge among infants born to mothers of various Asian/Pacific islander (PI) races.

STUDY DESIGN

In this retrospective cohort study, infants with weight <1500 g or 23-28 weeks gestation, born in California during 2008-2012 were included. Logistic regression models were used.

RESULTS

Asian and PI infants in ten groups had significant differences in growth parameters, socioeconomic factors, and some morbidities. Overall incidences of SGA at birth and discharge were 21% and 50%, respectively; Indian race had the highest numbers (29%, 63%). Infants of parents with the same race were at increased risk of SGA at birth and discharge compared with mixed race parents.

CONCLUSION

Specific Asian race should be considered when evaluating preterm growth. Careful consideration for the appropriateness of grouping Asian/PI races together in perinatal studies is warranted.

Adverse perinatal outcomes in immigrants: A ten-year population-based observational study and assessment of growth charts

BACKGROUND

Maternity populations are becoming increasingly multiethnic. Conflicting findings exist regarding the risk of adverse perinatal outcomes among immigrant mothers from different world regions and which growth charts are most appropriate for identifying the risk of adverse outcomes.

OBJECTIVE

To evaluate whether infant mortality and morbidity, and the categorisation of infants as small for gestational age or large for gestational age (SGA or LGA) vary by maternal country of birth, and to assess whether the choice of growth chart alters the risk of adverse outcomes in infants categorised as SGA and LGA.

METHODS

A population cohort of 601 299 singleton infants born in Australia to immigrant mothers was compared with 1.7 million infants born to Australian-born mothers, 2004-2013. Infants were categorised as SGA and LGA according to a descriptive Australian population-based birthweight chart (Australia-2012 reference) and the prescriptive INTERGROWTH-21st growth standard. Propensity score reweighting was used for the analysis.

RESULTS

Compared to Australian-born infants, infants of mothers from Africa, Philippines, India, other Asia countries, and the Middle East had between 15.4% and 48.1% elevated risk for stillbirth, preterm delivery, or low Apgar score. The association between SGA and LGA and perinatal mortality varied markedly by growth chart and country of birth. Notably, SGA infants from African-born mothers had a relative risk of perinatal mortality of 6.1 (95% CI 4.3, 6.7) and 17.3 (95% CI 12.0, 25.0) by the descriptive and prescriptive charts, respectively. LGA infants born to Australian-born mothers were associated with a 10% elevated risk of perinatal mortality by the descriptive chart compared to a 15% risk reduction by the prescriptive chart.

CONCLUSIONS

Country-of-birth-specific variations are becoming increasingly important for providing ethnically appropriate and safe maternity care. Our findings highlight significant variations in risk of adverse perinatal outcomes in immigrant subgroups, and demonstrate how the choice of growth chart alters the quantification of risk associated with being born SGA or LGA.

Birthweight of babies born to migrant mothers - What role do integration policies play?

Birthweights of babies born to migrant women are generally lower than those of babies born to native-born women. Favourable integration policies may improve migrants’ living conditions and contribute to higher birthweights. We aimed to explore associations between integration policies, captured by the Migrant Integration Policy Index (MIPEX), with offspring birthweight among migrants from various world regions. In this cross-country study we pooled 31 million term birth records between 1998 and 2014 from ten high-income countries: Australia, Belgium, Canada, Denmark, Finland, Japan, Norway, Spain, Sweden and United Kingdom (Scotland). Birthweight differences in grams (g) were analysed with regression analysis for aggregate data and random effects models.

Proportion of births to migrant women varied from 2% in Japan to 28% in Australia. The MIPEX score was not associated with birthweight in most migrant groups, but was positively associated among native-born (mean birthweight difference associated with a 10-unit increase in MIPEX: 105 g; 95% CI: 24, 186). Birthweight among migrants was highest in the Nordic countries and lowest in Japan and Belgium. Migrants from a given origin had heavier newborns in countries where the mean birthweight of native-born was higher and vice versa. Mean birthweight differences between migrants from the same origin and the native-born varied substantially across destinations (70 g–285 g).

Birthweight among migrants does not correlate with MIPEX scores. However, birthweight of migrant groups aligned better with that of the native-born in destination counties. Further studies may clarify which broader social policies support migrant women and have impacts on perinatal outcomes.

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Favourable migrant integration policies, as measured by the MIPEX, did not correlate with offspring birthweight among migrants.

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However, the MIPEX correlated with birthweight among the offspring of native-born women.

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Migrants' birthweights were higher in countries with high birthweights in the local population and vice versa.

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Birthweight among native-born seems to have a pull-effect on the birthweight of migrant groups.

Concomitant preterm birth and severe small-for-gestational age birth weight among infants of immigrant mothers in Ontario originating from the Philippines and East Asia: a population-based study

OBJECTIVES

Women from the Philippines form one of the largest immigrant groups to North America. Their newborns experience higher rates of preterm birth (PTB), and separately, small-for-gestational age (SGA) birth weight, compared with other East Asians. It is not known if Filipino women are at elevated risk of concomitant PTB and severe SGA (PTB-SGA), a pathological state likely reflective of placental dysfunction and neonatal morbidity.

METHODS

We conducted a population-based study of all singleton or twin live births in Ontario, from 2002 to 2011, among immigrant mothers from the Philippines (n=27 946), Vietnam (n=15 297), Hong Kong (n=5618), South Korea (n=5148) and China (n=42 517). We used modified Poisson regression to generate relative risks (RR) of PTB-SGA, defined as a birth <37 weeks' gestation and a birth weight <5th percentile. RRs were adjusted for maternal age, parity, marital status, income quintile, infant sex and twin births.

RESULTS

Relative to mothers from China (2.3 per 1000), the rate of PTB-SGA was significantly higher among infants of mothers from the Philippines (6.5 per 1000; RR 2.91, 95% CI 2.27 to 3.73), and those from Vietnam (3.7 per 1000; RR 1.68, 95% CI 1.21 to 2.34). The RR of PTB-SGA was not higher for infants of mothers from Hong Kong or South Korea.

INTERPRETATION

Among infants born to immigrant women from five East Asian birthplaces, the risk of PTB-SGA was highest among those from the Philippines. These women and their fetuses may require additional monitoring and interventions.

Scoping Review on Maternal Health among Immigrant and Refugee Women in Canada: Prenatal, Intrapartum, and Postnatal Care

The last fifteen years have seen a dramatic increase in both the childbearing age and diversity of women migrating to Canada. The resulting health impact underscores the need to explore access to health services and the related maternal health outcome. This article reports on the results of a scoping review focused on migrant maternal health within the context of accessible and effective health services during pregnancy and following delivery. One hundred and twenty-six articles published between 2000 and 2016 that met our inclusion criteria and related to this group of migrant women, with pregnancy/motherhood status, who were living in Canada, were identified. This review points at complex health outcomes among immigrant and refugee women that occur within the compelling gaps in our knowledge of maternal health during all phases of maternity. Throughout the prenatal, intrapartum, and postnatal periods of maternity, barriers to accessing healthcare services were found to disadvantage immigrant and refugee women putting them at risk for challenging maternal health outcomes. Interactions between the uptake of health information and factors related to the process of immigrant settlement were identified as major barriers. Availability of appropriate services in a country that provides universal healthcare is discussed.

[Epidemiology and risk factors of preterm birth]

OBJECTIVE

To synthesize the available evidence regarding the incidence and several risk factors of preterm birth. To describe neonatal outcomes according to gestational age and to the context of delivery.

MATERIALS AND METHODS

Consultation of the Medline database.

RESULTS

In 2010, 11% of live births (15 million babies) occurred before 37 completed weeks of gestation worldwide. About 85% of these births were moderate to late preterm babies (32-36 weeks), 10% were very preterm babies (28-31 weeks) and 5% were extremely preterm babies (<28 weeks). In France, premature birth concerns 60,000 neonates every year, 12,000 of whom are born before 32 completed weeks of gestation. Half of them are delivered after spontaneous onset of labor or preterm premature rupture of the membranes, and the other half are provider-initiated preterm births. Several maternal factors are associated with preterm birth, including sociodemographic, obstetrical, psychological, and genetic factors; paternal and environmental factors are also involved. Gestational age is highly associated with neonatal mortality and with short- and long-term morbidities. Pregnancy complications and the context of delivery also have an impact on neonatal outcomes.

CONCLUSION

Preterm birth is one of the leading cause of the under-five mortality and of neurodevelopmental impairment worldwide; it remains a major public health issue.

Health Services Utilization, Specialist Care, and Time to Diagnosis with Inflammatory Bowel Disease in Immigrants to Ontario, Canada: A Population-Based Cohort Study

BACKGROUND

Canada has amongst the highest incidence of inflammatory bowel disease (IBD) in the world, and the highest proportion of immigrants among G8 nations. We determined differences in prediagnosis delay, specialist care, health services use, and risk of surgery in immigrants with IBD.

METHODS

All incident cases of IBD in children (1994-2009) and adults (1999-2009) were identified from population-based health administrative data in Ontario, Canada. Linked immigration data identified those who arrived to Ontario after 1985. We compared time to diagnosis, postdiagnosis health services use (IBD specific and related), physician specialist care in immigrants and nonimmigrants, and risk of surgery between immigrants and nonimmigrants.

RESULTS

Thousand two hundred two immigrants were compared with 22,990 nonimmigrants. Immigrants had similar time to diagnosis as nonimmigrants for Crohn's (hazard ratio [HR] 1.002; 95% confidence intervals [CIs] 0.89-1.12) and ulcerative colitis (HR 1.073; 95% CI 0.95-1.21). For outpatient visits, immigrants with IBD were seen by gastroenterologists more often than nonimmigrants. Immigrants had greater IBD-specific outpatient health services use after diagnosis (odds ratio 1.24; 95% CI 1.15-1.33), emergency department visits (odds ratio 1.57, 95% CI 1.30-1.91), and hospitalizations (odds ratio 1.19; 95% CI 1.02-1.40). In immigrants, there was lower risk of surgery for Crohn's (HR 0.66, 95% CI 0.43-0.99) and ulcerative colitis (HR 0.52, 95% CI 0.31-0.87).

CONCLUSIONS

Immigrants to Canada had greater outpatient and specialty care and lower risk of surgery, with no delay in diagnosis, indicating appropriate use of the health system.

Maternal Origin and Risk of Neonatal and Maternal ICU Admission

OBJECTIVES

To evaluate maternal world region of birth, as well as maternal country of origin, and the associated risk of admission of 1) a mother to a maternal ICU, 2) her infant to a neonatal ICU, or 3) both concurrently to an ICU.

DESIGN

Retrospective population-based cohort study.

SETTING

Entire province of Ontario, Canada, from 2003 to 2012.

PATIENTS

All singleton maternal-child pairs who delivered in any Ontario hospital.

MEASUREMENTS AND MAIN RESULTS

We explored how maternal world region of birth, and specifically, maternal country of birth for the top 25 countries, was associated with the outcome of 1) neonatal ICU, 2) maternal ICU, and 3) both mother and newborn concurrently admitted to ICU. Relative risks were adjusted for maternal age, parity, income quintile, chronic hypertension, diabetes mellitus, obesity, dyslipidemia, drug dependence or tobacco use, and renal disease. Compared with infants of Canadian-born mothers (110.7/1,000), the rate of neonatal ICU admission was higher in immigrants from South Asia (155.2/1,000), Africa (140.4/1,000), and the Caribbean (167.3/1,000; adjusted relative risk, 1.41; 95% CI, 1.36-1.46). For maternal ICU, the adjusted relative risk was 1.79 (95% CI, 1.43-2.24) for women from Africa and 2.21 (95% CI, 1.78-2.75) for women from the Caribbean. Specifically, mothers from Ghana (adjusted relative risk, 2.71; 95% CI, 1.75-4.21) and Jamaica (adjusted relative risk, 2.74; 95% CI, 2.12-3.53) were at highest risk of maternal ICU admission. The risk of both mother and newborn concurrently admitted to ICU was even more pronounced for Ghana and Jamaica.

CONCLUSIONS

Women from Africa and the Caribbean and, in particular, Ghana and Jamaica, are at higher risk of admission to ICU around the time of delivery, as are their newborns.