Study population
82 mother-child data pairs were included. Patients were recruited at multiple sites in Germany (Jena (n = 35) 42.7%, Walsrode (n = 21) 25.6%, Halle (n = 13) 15.9%, Munich (n = 8) 9.8% and Berlin (n = 5) 6.1%).
The demographic characteristics of migrant women and details of the migration route are shown in Table
1. Most frequent countries of origin were Syria (35.4%) and Somalia (12.2%). Migration from African countries was observed in 40 cases (48.8%) and from Oriental Asian countries in 42 cases (51.2%).
Table 1
Characteristics of migrant women and their migration route
Age [years; median (IQR)] | 27 (11.0) |
Weight [kg; median (IQR)] | 67.5 (25.0) |
BMI [kg/m2; median (IQR)] | 24.42 (7.89) |
Year of migration to Europe; median (IQR) | 2015 (2.0) |
Ethnicity [n (%)] | Oriental Asian | 40 (48.8) |
African | 23 (28.0) |
Caucasian | 14 (17.1) |
other | 5 (6.1) |
Most frequent countries of origin [n (%)] | Syria | 29 (35.4) |
Somalia | 10 (12.2) |
Nigeria | 9 (11.0) |
Transportation during migration [n (%)] (multiple answers possible) | by car | 16 (19.5) |
foot | 20 (24.4) |
by airplane | 39 (47.6) |
by boot | 22 (26.8) |
train | 22 (26.8) |
Perinatal/neonatal outcomes
52% of newborns were male. The delivery mode was spontaneous in 57.3% and assisted vaginal delivery in 2.4%. Primary caesarean section and secondary caesarean section were performed in 18.3 and 22%, respectively. Median gestational age was 39.71 weeks (IQR 2.43). Median length of newborns was 51 cm (IQR 3.0). Median birth weight and head circumference were 3318 g (IQR 623) and 35 cm (IQR 2.0), respectively. Median placental weight was 500 g (IQR 105.0). Median Apgar after five and ten minutes was 10 (IQR 1 and 0). Admission to NICU was reported in 21%. No newborns died. Median umbilical cord pH was 7.29 (IQR 0.14). Preterm birth (< 37 week) occurred in 5 cases (6.1%). Median gestational age for preterm birth was 32.3 weeks (IQR 6.5). Low birth weight (< 2500 g) occurred in 5 cases (6.1%), 4 of these were preterm. Median weight for low birth weight was 1700 g (IQR 1265). Median percentile for weight was 35.0 (IQR 37.25). Median percentile for height was 38 (IQR 40.00) and median percentile for head circumference was 42.5 (IQR 41.25).
Birth weights below the 10th percentile of birth weight for gestational age were observed in 8.5% (n = 7) of the cohort. There was no preterm birth (< 37 week) below 10th percentile of birth weight for gestational age. Gender-specific analysis showed a difference between female (4.7%) and male (12.8%) newborns (5 vs. 2). However, the gender difference was not significant (p = 0.25). Thus, we observed a fetal growth restriction (> 10% below the 10th birth weight percentile) for newborn boys in our migrant population.
Univariate regression models for the birth weight percentile outcome revealed significant influence of: mother’s height, mother’s weight at delivery, transport to Europe by foot, transport to Europe by boat, number of previous pregnancies and number of previous birth (p ≤ 0.05 for all). Univariate regression models for birth weight revealed significant influence of: pregnancy induced hypertension, preeclampsia, previous diabetes, previous hypertension, transport to Europe by foot and number of previous birth (p ≤ .05 for all, data not shown).
In the multiple linear regression models on birth weight percentiles with the factors transport to Europe by foot, number of previous births and mother’s weight at delivery, a quality of 0.30 (adjusted R-square) was achieved. The results of the analysis are shown in Table
2. A significant positive effect could be demonstrated for all three factors (each
p < .01). Transport to Europe by foot and number of previous births turned out to be equally strong (both standardized regression coefficients are 0.28 and 0.27) whereby weight at delivery with beta = 0.33 shows a comparatively higher value. The non-standardized regression coefficients B show the change in the dependent variable in one step change in the factor. If the weight of the mother at delivery increases by one unit (kilograms), the birth weight percentile increases by 0.56 units (percentiles). I.e. if the weight increases by 2 kg on delivery, the birth weight is one percentile higher. The same applies vice versa: if the weight of the mother on delivery drops by 2 kg, the birth weight is one percentile lower. If the number of previous births increases by one unit, the birth weight is 5.8 percentiles higher. The opposite applies again when the number of previous births is one unit lower. If the transport to Europe was by foot (nominal variable), the birth weight was 16.1 percentiles higher than for migrants who used another means of transport.
Table 2
Influence of various independent variables on birth weight percentiles - Results of the multiple linear regression models
Non-standard coefficients | Regression coefficient B | 16.084 | 5.803 | 0.545 |
| Standard Error | 5.607 | 2.152 | 0.163 |
standard coefficient | Beta | 0.278 | 0.271 | 0.333 |
Significance | p | 0.005 | 0.009 | 0.001 |
95.0% Confidence intervals for B | lower limit | 4.910 | 1.515 | 0.220 |
upper limit | 27.258 | 10.091 | 0.869 |
Collinearity statistics | VIF | 1.018 | 1.097 | 1.079 |
There were seven cases of FGR (birth weight < 10th percentile) in the cohort. The numerically higher number of mothers immigrated from Syria (Syria: n = 4, Somalia, Nigeria and other countries respectively n = 1) is statistically insignificant (p = 0.277). Furthermore, there is no difference in occurrence after stratification by ethnicity (Oriental-Asian: n = 4 (10%), African-American: n = 3 (13%); p = 0.705).
Correlation analyses according to Kendall-Tau-B showed no correlation between birth weight and ethnicity (p = 0.393) and only a very weak correlation between birth weight and country of origin (r = 0.169; p = 0.05), which, however, is no longer evident when stratified by the respective country of origin (Nigeria, Somalia and Syria). Regression analyses showed that the different ethnicities do not differ in the degree of influence on the birth weight percentiles. Furthermore, it can be shown that none of the countries of origin has an influence on the birth weight percentiles (p > .7 for all).