Interbirth Intervals of Immigrant and Refugee Women in the United States: A Cross-Sectional Study

1. Introduction

Current guidelines recommend an interval of at least 18–24 months between a live birth and the conception of the next pregnancy.1,2 However, nearly one-third of pregnancies in the United States are conceived within 18 months of a previous birth.3 Short interbirth interval is associated with adverse birth and infant outcomes and increased risks of maternal morbidity during pregnancy and at delivery.4-8 Moreover, most of the adverse outcomes of short interval births are concentrated in marginalized populations, including immigrants.9,10

Factors associated with short interbirth interval include younger maternal age, marital status, and delayed initiation of childbearing.6,7 Short duration of, or non-exclusive breastfeeding, and prior experience of infant death or pregnancy loss are also associated with short interpregnancy intervals.11-13 Importantly, unintended pregnancies have significantly shorter birth intervals than planned pregnancies.6,14 Other factors associated with short interbirth intervals include race and ethnicity and lower socioeconomic status.7,11,15 Hispanic and Black individuals have comparatively higher risks of short interval births.6,11

Although health is a public good and health care should be universally available and accessible to individuals and communities, some groups of the population face significant barriers to accessing health care services.16-18 For example, marginalized populations, such as immigrant and refugee communities, face barriers to health care, particularly sexual and reproductive health (SRH) care, due to language barriers, cultural norms, unfamiliarity with the US health care system, lower socioeconomic status, and a lack of culturally appropriate services.19-22 In addition, due to the intersecting influences of immigration policies, language, and socioeconomic barriers, immigrant and refugee populations have even less access to health care services, including SRH and contraception.19-21,23

Federal immigration laws in the United States prevent undocumented immigrants and documented immigrants who have been in the country for less than 5 years from enrolling in publicly funded health insurance programs offered through Medicaid.24,25 Access to essential health education and services, such as SRH care, family planning services, and contraception for spacing or limiting births, is extremely limited for low-income immigrant and refugee women unless state exemptions are available.26 Moreover, a lack of culturally competent health care providers and racism directed at immigrants constitute additional barriers to SRH care and optimal birth spacing in this population.26 Consequently, individuals from immigrant and refugee populations are more likely to report using less effective contraception methods, which may increase their risk for short interval births.27 Studies on interbirth intervals involving immigrant and refugee women have mostly relied on birth certificate data, which lack a number of key sociodemographic variables, thereby limiting the ability to adequately adjust the analyses for potential confounding factors.10,28,29

The purpose of this study, therefore, was to examine the associations between multiple immigration-related variables and interbirth interval among immigrant and refugee women living in the United States. The findings can contribute to filling some knowledge gaps about the factors associated with short interbirth intervals in immigrant and refugee women and identify groups at higher risk for short interbirth interval.

2. Methods

This was a cross-sectional, quantitative study on the sexual and reproductive health of immigrant women in the United States (n = 657). The data were collected via an online survey administered by Lucid LLC, which supports the recruitment of samples for academic research through its academic marketplace, Theorem.30 Lucid is able to reach and recruit diverse audiences through partnerships with multiple vendors. Eligibility for the online survey was based on self-identification as a woman, aged 18–44 years, English proficiency, and residency in the United States. We included data on 653 women who had complete information on nativity and birth history in the descriptive analysis (n = 653). For the regression analysis, we excluded women with fewer than two births (n = 408); hence, the final analytic sample was 245 women with two or more births.

3. Results

3.2. Frequency Distribution of Interbirth Intervals of Women in the Study

Approximately 37.4% of the study participants had an interbirth interval of ≤18 months, 23.7% had interbirth intervals of 19–35 months, and 39.0% reported interbirth intervals of ≥36 months (Figure 1).

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Figure 1

Frequency distribution of interbirth interval among women in the study (n = 245)

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4. Discussion

We examined the relationships between immigration-related factors and interbirth interval among women living in the United States. The results revealed that more than a third (37.4%) of births occurred within 18 months of a previous live birth. We also found significant relationships between immigration pathway and place of birth with interbirth intervals, but no relationship between the length of time since immigrating to the United States and outcome.

Our findings contribute to the literature on birth interval not only in the general US populations but also in the country’s immigrant and refugee populations. We found a slightly higher prevalence of short interval births (37%) than the national average of approximately 30%14 and population-based studies that reported interbirth intervals ranging from 11% to 35%.6,14,29 Studies have reported an above-average prevalence of short birth intervals in Black people, including Black immigrants.6,10,37 Because Black women were overrepresented in our sample, this may have contributed to the higher prevalence of short interbirth intervals (≤18 months) observed in the results of the present study.

After adjusting for potential confounders, the association between shorter duration of time since immigration to the United States and interbirth interval lost significance. The length of time since immigration has been linked to health beliefs and behaviors, such as the use of disease management and preventative services for physical, mental, and sexual and reproductive health.23,38-40 The length of stay in the receiving country has been used to asses acculturation and how immigrants change over time as a result of contact with other cultures after immigration.23,41 It has also been linked to immigrants’ initial health advantage, and health deterioration has been linked to longer duration of stay as a result of exposure to social and environmental determinants of health.42 Simbiri et al.23 argue in a study on care seeking that length of stay in the United States was not as important as language proficiency for immigrants accessing HIV prevention and care services. In the present study, nearly 87% of participants reported speaking English predominantly at home. Hence, adjusting the analysis for language spoken predominantly at home could have contributed to the null results we observed. We are not aware of any previous studies that examined associations between length of stay and interbirth interval in the United States. Nevertheless, this result warrants further investigation and confirmation using larger population-based data sets.

Our results revealed that a woman’s place of birth was associated with interbirth interval. Women born in an African country had lower odds of reporting longer interbirth intervals (i.e., 19–35 or ≥36 months) than the unexposed group (i.e., US-born women). Our result indicating shorter interbirth interval among African-born women is consistent with the results of previous studies that reported shorter interpregnancy intervals among African-born women relative to women born in the United States and other parts of the world.10,28 Specifically, Zhang et al.10 found that African-born women had a mean birth-to-pregnancy interval that was about 6.5 and 15.4 months shorter than those of US-born White and Black women, respectively. Similarly, another study in Utah found that African-born women had higher parities and shorter intervals between pregnancies than White women born in the United States.43 The authors suggested that their finding could be due to religious beliefs, cultural preferences for large families, and a lack of access to family planning methods, consistent with the existing literature.23,28,43-46

Women who immigrated to the United States for educational or employment opportunities had significantly longer interbirth intervals than women born in the United States. We are not aware of any previous studies that examined interbirth intervals in people who migrated to the United States for educational or employment opportunities. This result is plausible because student visa policies require good academic standing, which may be hampered by closely spaced pregnancies and the cost of childcare, which may be unaffordable to most international students.47,48 The same argument may be true for women who immigrated for employment opportunities, in which case, closely spaced pregnancies may interfere with employment prospects. Taken together, voluntary immigrants, regardless of immigration pathway, may have greater motivation and self-efficacy to space childbearing in order to avoid jeopardizing their visa status due to the physical, financial, and social implications of pregnancy, birthing, and childcare.48,49

The results also indicated that women who migrated to the United States due to conflict or persecution had no significantly different odds of being in longer interbirth interval categories than women born in the United States. A recent study of Somali and Congolese refugee women found that the lasting influence of cultural identity and birth spacing norms, post-resettlement, contribute to the use of less effective contraceptive methods (e.g., condoms, withdrawal, oral contraceptives, and fertility awareness methods) during the postpartum period.50 Some of these methods, if not used correctly and consistently, may contribute to short interbirth intervals in immigrant and refugee women. However, our results do not support this explanation and warrants further investigation.

5. Conclusion and Global Health Implications

In this study, we examined the associations between immigration-related factors and interbirth intervals of immigrant and refugee women living in the United States. We found that the prevalence of short interval births was higher in this sample than the national average. The study’s key findings revealed that women who immigrated for educational or employment opportunities had significantly higher odds of reporting longer interbirth intervals than women born in the United States. Our findings contribute to our understanding of the interbirth intervals of immigrant and refugee women in the United States. Because immigration is becoming an increasingly important health determinant,21 the various immigration pathways should be considered when planning and delivering health services to foreign-born women in the United States. Our results also indicated that women born in Africa have shorter interbirth intervals than other women in the sample. Despite rapid growth in African immigration to the United States in recent years, the population has remained underrepresented in health research and services.51,52 As immigration from sub-Saharan Africa to the United States continues, there is a need for more research to understand this population’s SRH needs to provide responsive reproductive health care. While our study provides preliminary insights into immigration-related factors associated with interbirth interval among immigrant and refugee women in the United States, more research focusing on specific immigrant groups who may be at increased risk for short interbirth interval and its associated implications for pregnancy and birth outcomes is needed. Future research should prioritize African-born immigrant and refugee women, as well as recent immigrants.