Introduction

Over the last two decades, caesarean birth (CB) rates have increased dramatically in most high-income countries (HICs) . Although rates have remained relatively low in some countries such as Norway (16.6%), Sweden (16.3%) and the Netherlands (15.6%), current rates in the US, Canada, Australia and a number of countries in central and southern Europe have reached 25% or higher . While it is debated whether an optimal CB rate should be proposed, it has been shown that at the population level, rates above 10–15% are higher than can be medically justified .

The high CB rates in HICs are considered a source of public health concern due to associated health risks. Maternal health risks include infection, wound haematoma, increased blood loss, thromboembolism, surgical injury, a lengthy recovery and higher rates of maternal death . Complications in subsequent pregnancies include uterine rupture, stillbirth, placenta previa, placental abruption and invasive placental disease . For newborns, there is a greater risk of respiratory problems, admission to a neonatal intensive care unit (NICU) and perinatal mortality .

A CB is also a costly procedure . Costs include the material and human resources associated with performing the procedure, a longer hospital stay and hospital readmissions due to complications. Given the associated health risks and costs, and the fact that some countries with low CB rates also have low perinatal mortality rates , high CB rates have been questioned, and recommendations issued that CBs only be undertaken when medically necessary .

Worldwide, there are over 135 million international migrants living in HICs, half of whom are women . ‘International migrants’ (hereafter referred to as ‘migrants’) are individuals who have moved from one country to establish themselves temporarily or permanently in another country . The majority of migration is from low- and middle-income countries (LMICs) . In some HICs, births to migrants represent 20% or more of all births . Both the migrant population and the number of births among migrant women are expected to grow.

CB rates of migrants living in HICs are not readily available in government reports and statistics. Based on the most recent data available from published studies , the population rates for migrants are generally well above the recommended 10–15% range, although they appear to vary according to the rates of the receiving countries. Data also suggest that rates vary for different migration subpopulations defined by migration indicators including country of birth, length of time in receiving country and migration classification (e.g., economic immigrant and refugee). A number of studies also show higher rates for certain migrant groups when compared with non-migrant women .

Although migrants are often healthier than non-migrants upon arrival (i.e., the ‘healthy-immigrant effect’), many migrant women, especially from LMICs, face conditions that may exacerbate health and childbearing risks including poverty, social isolation, discrimination, limited or no health insurance, barriers to accessing health care and stress related to migration and resettlement . ‘Humanitarian migrants’, including refugees, those seeking asylum (i.e., those applying for refugee status at the border or from within the receiving country) and undocumented persons (i.e., those individuals with no legal status in the receiving country) may have suffered violence and trauma . Risks for various diseases may also vary between different migrant subgroups depending on their country of origin, their migration trajectory and genetic predisposition.

In this context, CB rates among migrant women in HICs are of concern. This review aims to provide a synthesis of what is known regarding CBs among migrants living in HICs, and it offers recommendations for clinical care to improve childbirth outcomes in migrant women. Agreed migrant indicators (i.e., country of birth, length of time in receiving country, language fluency and ethnicity) have guided the focus of the review , with the exception of ethnicity as it is a concept that applies both to migrants and to non-migrants, and it is often conflated with the country of birth.

CB rates: migrants compared with non-migrants

A systematic review and meta-analysis comparing CB rates of migrants by region/country of origin to non-migrants living in HICs was published in 2013 . The search was exhaustive (to January 2012), and it had no language restrictions. The primary inclusion criterion was that studies must have examined migrants living in an HIC and included comparison caesarean data on non-migrant women. Migrant and non-migrant groups had to be mutually exclusive (i.e., foreign born and native born, respectively).

Seventy-six studies were included in the review:

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  Over two-thirds were conducted in Europe, 11% were conducted in Australia, 11% in the US and the remaining were done in Canada and Israel

  
  
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  Data sources were population based in 36% of studies

  
  
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  Seventy per cent of the data were from the 1990s or later

  
  
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  The most studied groups were migrants from sub-Saharan Africa (33 studies), North-Africa/Middle East (32 studies), East/South-East Asia (26 studies) and Eastern Europe (26 studies)

Comparisons of CB rates between migrant and non-migrant women were categorized as ‘higher’, ‘lower’ or ‘no different’ for each study. For studies comparing rates of more than one migrant group, studies were categorized as ‘higher’, ‘higher and no different’, ‘lower’, ‘lower and no different’, ‘mixed’ or ‘no different’:

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  Overall CB rates were higher or higher and no different in 39% of studies; lower or lower and no different in 17% of studies; and mixed in 13% of studies

  
  
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  For emergency CBs ( N = 21), more than half of the studies showed migrants to have higher (or higher and no different) rates

  
  
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  For planned CBs ( N = 19), results were more varied: 26% showed higher (or higher and no different) rates, 37% showed lower (or lower and no different) rates, 32% showed that migrants were similar to non-migrants and 5% had mixed results

  
  
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  Meta-analyses revealed that women from sub-Saharan Africa and South Asia were consistently at a greater risk of CBs overall as were North African/Middle-Eastern and Latin American women for emergency CBs; Vietnamese and Eastern European women showed reduced risk

CB rates: migrants compared with non-migrants

A systematic review and meta-analysis comparing CB rates of migrants by region/country of origin to non-migrants living in HICs was published in 2013 . The search was exhaustive (to January 2012), and it had no language restrictions. The primary inclusion criterion was that studies must have examined migrants living in an HIC and included comparison caesarean data on non-migrant women. Migrant and non-migrant groups had to be mutually exclusive (i.e., foreign born and native born, respectively).

Seventy-six studies were included in the review:

• •
  

  Over two-thirds were conducted in Europe, 11% were conducted in Australia, 11% in the US and the remaining were done in Canada and Israel

  
  
• •
  

  Data sources were population based in 36% of studies

  
  
• •
  

  Seventy per cent of the data were from the 1990s or later

  
  
• •
  

  The most studied groups were migrants from sub-Saharan Africa (33 studies), North-Africa/Middle East (32 studies), East/South-East Asia (26 studies) and Eastern Europe (26 studies)

Comparisons of CB rates between migrant and non-migrant women were categorized as ‘higher’, ‘lower’ or ‘no different’ for each study. For studies comparing rates of more than one migrant group, studies were categorized as ‘higher’, ‘higher and no different’, ‘lower’, ‘lower and no different’, ‘mixed’ or ‘no different’:

• •
  

  Overall CB rates were higher or higher and no different in 39% of studies; lower or lower and no different in 17% of studies; and mixed in 13% of studies

  
  
• •
  

  For emergency CBs ( N = 21), more than half of the studies showed migrants to have higher (or higher and no different) rates

  
  
• •
  

  For planned CBs ( N = 19), results were more varied: 26% showed higher (or higher and no different) rates, 37% showed lower (or lower and no different) rates, 32% showed that migrants were similar to non-migrants and 5% had mixed results

  
  
• •
  

  Meta-analyses revealed that women from sub-Saharan Africa and South Asia were consistently at a greater risk of CBs overall as were North African/Middle-Eastern and Latin American women for emergency CBs; Vietnamese and Eastern European women showed reduced risk

Review update

Using the same inclusion criteria as the systematic review, electronic databases were searched to identify additional studies published between 2012 and 2015. Thirty-three studies were identified .

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  Twenty-two studies were conducted in Europe, four in Australia, three in Israel and two each in the US and Canada; one study was conducted in Japan

  
  
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  Just over half included population-based data

  
  
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  All included data from 2000 or later

  
  
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  The migrant groups studied most were women from sub-Saharan Africa (20 studies), North Africa/Middle East (16 studies), South/Central America and Mexico (15 studies) and Eastern Europe (14 studies)

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  Overall CB rates were higher or higher and no different in 30% of studies; lower or lower and no different in 17% of studies; and mixed in 30% of studies

  
  
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  For emergency CBs ( N = 13), 77% showed rates to be higher or higher and no different, and the remaining studies showed mixed results

  
  
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  For planned CBs ( N = 12), 17% showed rates higher or higher and no different; 25% were lower or lower and no different; 33% were mixed results; and 25% showed no differences in CB rates

  
  
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  Several studies showed that migrant women from sub-Saharan Africa to have a greater risk of a CB , and Eastern European women to have a reduced risk . Results regarding migrants from other regions were insufficient and/or too heterogeneous to draw firm conclusions.

To summarize, migrant women from Sub-Saharan Africa and South Asia consistently show an increased risk, and women from Eastern Europe and Vietnam a reduced risk, when compared to non-migrant women. Migrant women from Latin America and North Africa/Middle-East show higher emergency caesarean rates when compared to non-migrant women. Higher emergency CB rates appear to be more of an issue rather than planned caesareans. Limitations of the research conducted to date are the heterogeneity in how migrant populations are defined (e.g., large populations grouped together as ‘foreign born’; countries/regions grouped differently across studies) and a lack of studies from North America. Only a small number of studies examined more specific migration indicators (i.e., country of origin, length of time and migration classification), and so differences within migrant populations from the same region may have been masked. Studies also have variation in which women were included (e.g., low risk), and how CBs were classified/defined (e.g., pre-labour vs. during labour; Robson classification; emergency vs. planned; all caesareans grouped together).

Indications and pathways leading to high CB rates among migrants

Studies show that the most common indications for CBs among migrants are repeat caesareans, failure to progress (FTP)/dystocia, fetal distress and cephalo-pelvic disproportion (CPD) . It is unclear what additional factors may be driving the high rates among migrants specifically as studies comparing between migrant subpopulations defined by migration indicators are insufficient , and only one study examining predictors of CBs (emergency caesarean) in migrants was found . Evidence to explain high caesarean rates among migrant women therefore is lacking, although a number of potential contributing factors have been identified . Those most frequently cited can be grouped into six broad categories: poor maternal health , high body mass index (BMI) and gestational diabetes mellitus (GDM) , women’s cultural attitudes and expectations regarding labour and delivery management , acculturation , genital cutting and language and cultural barriers, and quality of care .

Poor maternal health

It is not known whether some migrant women may have a greater medical need for a caesarean. Studies identified in the literature search did not provide any consistent evidence that migrant women require more caesareans due to placental complications, or medical conditions such as pre-eclampsia. A number of authors, however, did suggest (in discussion) that women’s general health status due to other diseases, which were not measured or controlled for in analyses, for example, infectious diseases or anaemia, may have a role . Infectious diseases including hepatitis B and C, parasitic infections and anaemia are conditions known to disproportionately afflict migrants compared with non-migrants, and migrant women of reproductive age are particularly susceptible to iron-deficiency anaemia . Human immunodeficiency virus (HIV), a known indication for a caesarean, is also known to be more prevalent in migrants . Humanitarian migrants or those coming from LMICs may be particularly vulnerable to exposure to diseases . Low socio-economic status (SES), lack of insurance and reduced access to health care, including prenatal care , may also exacerbate poor maternal health. Gillet et al. (2014) found that migrants from low-income countries were at an increased risk of an emergency caesarean compared with non-migrant women; Kandasamy et al. (2014) found asylum-seeking/refugee women to have a greater risk of caesarean compared with Canadian-born and other migrant women , and Gagnon et al. (2013) found low SES and not having health insurance to be independent predictors of emergency caesarean among migrant women giving birth in Canada suggesting that the high-risk health/social profile of these women may have had some role in their risk of caesarean . Conversely, Gagnon et al. (2013) found that refugees and asylum seekers were at a reduced risk of an emergency caesarean compared with economic and student migrants , and an Australian study comparing migrant women from humanitarian and non-humanitarian source countries found the latter to have higher caesarean rates . Another Canadian study showed caesarean rates by migration classification to vary based on women’s country of birth . The inconsistent findings and the use of more social indicators as markers of a poor health status make it difficult to draw conclusions. A CB associated with a ‘humanitarian’ migration classification or low SES may not be due to a high-risk health profile but rather it may be due to other reasons such as how these women were cared for and supported.

BMI and GDM

A greater prevalence of excess weight and obesity among certain groups of migrant women, including women from sub-Saharan Africa, and North Africa, as well as migrant women arriving from ‘humanitarian’ source countries, has been shown . Adoption of more ‘Western’ dietary habits and sedentary lifestyles has been cited as one of the possible causes of migrants having/gaining excess weight . Gagnon et al. (2013) found higher rates of obesity among migrant women who had an emergency caesarean compared with migrant women who had a planned caesarean or a vaginal birth. In multivariable analyses, however, obesity did not remain a significant factor although birth weight of >4000 g did . Other research that controlled for BMI also suggests that excess weight may be a contributing factor to high CB rates for some migrants .

GDM has been shown to be a greater burden for migrant women compared with non-migrant women in HICs . Evidence to explain higher rates of GDM among migrants is lacking, but it may be due to childhood malnutrition and/or a low social status . Studies show that migrant women with GDM have high CB rates. When compared with non-migrants, results are mixed (higher, lower and no different rates) , suggesting variation in care factors and thresholds of intervention for migrant women with GDM.

Women’s cultural attitudes and expectations regarding labour and delivery management

Culture and women’s experiences before migration affect expectations of maternity care. Some women migrate from countries such as Brazil, which is known to have a very high caesarean rate and where it appears to be culturally preferred to have a caesarean . Studies controlling for medical factors and showing higher caesarean rates among women from South America compared with non-migrants provide some support for this notion . Conversely, consistently lower rates of CB among migrants from Eastern Europe have been suggested to be due to their cultural preference for less interventionist care .

A large Norwegian study including women from 133 countries found evidence that the caesarean rate of a migrant woman’s country of origin is associated with her likelihood to have a CB . The premise was that the country of origin’s caesarean rate (high or low) was representative of a woman’s preference (or non-preference) for a CB, and this influenced the birth outcome accordingly. Although the country of origin may not be equivalent to a woman’s preference, women coming from countries where caesareans are the norm may have a lower threshold for intervention. Alternatively, care providers may know which countries have high caesarean rates, and they may have a lower threshold for intervention if they believe women from these countries prefer, or are more accepting of having a CB. Caesarean rates in the country of origin, however, do not explain caesarean rates in the receiving country for all migrant women as women from sub-Saharan Africa consistently show higher rates than non-migrants, and caesarean rates in Africa are low . Research on migrant women’s views on CB is limited, and it suggests that some prefer a CB whereas others do not .

Acculturation

‘Acculturation’ refers to the extent to which women have adopted the attitudes, behaviours and traditions of the receiving country. The younger the age at migration and the longer a woman has resided in the receiving country, the more likely she is to integrate and to take on the lifestyle behaviours and attitudes of the receiving country. With increasing time in the receiving country or language fluency, women are more likely to adopt Western dietary habits, smoking and drinking consumption may increase and they may become more sedentary. Stress associated with resettlement may also take a toll on maternal physical and mental well-being. In contrast to those migrant women who bring cultural preference for caesarean, other women who come from countries where caesarean rates are low may develop greater acceptance of intervention with time, or they may even seek intervention if this is viewed as being associated with a higher social status or better care.

The association between acculturation and CB risk has been studied using the length of time in the receiving country and receiving-country language fluency – although the latter is not an optimal measure for acculturation as migrants may speak the receiving-country language, but they may be very culturally divergent from the receiving-country population. Results from these studies are varied, and they suggest that different migrant subpopulations adapt differently with time and/or language fluency . Greater ‘acculturation’ was associated with higher CB rates for some migrants but not for others . One US study showed primiparous Mexican-born migrant women with greater language ability to have less risk of a CB . For multiparous women, CB rates were similar between Spanish-speaking and bilingual (English/Spanish) women. Differences by parity suggest previous birth experiences, and where they occurred may also have an influence on birth outcome.

Other studies have compared the CB rates of migrant women with shorter and longer lengths of residence to non-migrant women, and they also found diverging results . Although increased risk with longer lengths of time may be due to acculturation, increased risks associated with shorter lengths of time may be due to lack of familiarity with the health-care system, less support and access to care, stress related to migration and consequently a more stressful pregnancy and labour.

Genital cutting

Several obstetrics’ organizations in HICs have reviewed the literature and developed guidelines regarding genital cutting . Research shows that genital cutting is associated with an increased risk of a CB; however, there is inconsistent evidence as to whether a prolonged labour, which would lead to the caesarean, is associated with genital cutting in HICs. Many women who have experienced genital cutting prefer a vaginal birth, and they fear having a caesarean. In countries where genital cutting is practised, many births occur without the presence of skilled birth attendants, and women who undergo a CB die during childbirth. Migrant women attempting to avoid having a CB have been associated with an increased risk of having an emergency caesarean and perinatal death . Insensitivity and improper care of women with genital cutting in general are therefore more likely the explanation of high CB rates among these women rather than the scar itself .