Embla Ýr Guðmundsdóttir^1,2

Lilja Vigfúsdóttir³

Helga Gottfreðsdóttir^1,4

¹Department of Midwifery, Faculty of Nursing and Midwifery, University of Iceland, Iceland, ²The Reykjavík Birth Center, Iceland, ³The Health Directorate of East Iceland, Iceland, ⁴Department of Obstetrics and Gynecology, Women´s Clinic, Landspítali University Hospital, Iceland.

Correspondence: Embla Ýr Guðmundsdóttir, emblayrg@gmail.com

Key words: preterm birth, migrant women, risk factors, antenatal care.

INTRODUCTION: Migrant women often experience worse perinatal outcomes during pregnancy, birth, and puerperium than native women, but results regarding preterm birth vary. The objective of this study was to detect the prevalence and risk factors of preterm birth among Icelandic and migrant women in Iceland.

MATERIAL AND METHODS: The study was a population-based cohort study with data from the Icelandic Medical Birth Register. The cohort included all women who had a singleton birth from 22w0d to 36w6d of pregnancy in the years 1997-2018, a total of 89 170 women. The group was divided in two; women with an Icelandic citizenship and women with foreign citizenship, that were further divided according to the Human Development Index (HDI) of their country of citizenship. Preterm birth rate and risk factor prevalence was analysed according to this classification and significance in differences measured with a chi-square test.

RESULTS: Significance in differences of preterm birth was found between Icelandic (4.4%) and migrant women (5.6%) (p<0.001). Migrant women from middle-HDI countries gave birth preterm in 5.5% of cases (p<0.01) and women from low-HDI countries in 6.4% of cases (p<0.001). Migrant women were more often diagnosed with urinary tract infections, diabetes, intrauterine growth restriction and premature rupture of membranes, but less often with pre-eclampsia, obesity, placental defect, mental health issues and age <18 years (p<0.05).

CONCLUSION: Migrant women in Iceland from middle-HDI and low-HDI countries give birth preterm more often than Icelandic women. A difference in risk factors is also present and needs further research. The findings can be used in continuing development of prenatal care for migrant women in Iceland.

Table I. Background variables of women who gave birth prematue in Iceland during 1997-2018.

	Total (n=4021)		Icelandic (n=3582)		Migrant (n=439)			High HDI ≥0.900 (n=83)			Middle HDI 0.850-0.899 (n=218)			Low HDI ≤0.849 (n=115)
	n	%	n	%	n	%	p	n	%	p	n	%	p	n	%	p
Marital status
Married/ cohabiting	1466	36.5	1261	35.2	205	62.9	<0.001	29	45.3	0.094	90	57.3	<0.001	77	82.8	<0.001
Not married/ cohabiting	2441	60.7	2320	64.8	121	37.1		35	54.7		67	42.7		16	17.2
Missing	114	2.8	1	0.0	113	25.7		19	22.9		61	28.0		22	19.1
Residence
Capital area	2514	62.5	2258	63.0	256	58.3	0.054	39	47.0	0.003	134	61.5	0.641	74	64.3	0.774
Rural	1507	37.5	1324	37.0	183	41.7		44	53.0		84	38.5		41	35.7
Missing	0	0.0	0	0.0	0	0.0		0	0.0		0	0.0		0	0.0
Employment
Employed/ student	3402	84.6	3067	85.6	335	76.3	<0.001	61	73.5	0.002	174	79.8	0.019	88	76.5	0.007
Not employed/ student	619	15.4	515	14.4	104	23.7		22	26.5		44	20.2		27	23.5
Missing	0	0.0	0	0.0	0	0.0		0	0.0		0	0.0		0	0.0
Parity
Primipara	2014	50.1	1745	49.0	260	59.2	<0.001	44	53.0	0.466	134	61.5	<0.001	67	58.3	0.050
Multipara	2007	49.9	1828	51.0	179	40.8		39	47.0		84	38.5		48	41.7
1	1068	26.6	945	26.4	123	28.0	<0.001	22	26.5	0.799	64	29.4	<0.001	32	27.8	0.040
2	621	15.4	578	16.1	43	9.8		12	14.5		17	7.8		13	11.3
3+	318	7.9	305	8.5	13	3.0		5	6.0		3	1.4		3	2.6
Missing	0	0.0	0	0.0	0	0.0		0	0.0		0	0.0		0	0.0
Age
≤20 years	294	7.3	273	7.6	21	4.9	0.151	4	4.8	0.080	14	6.4	0.902	2	1.7	0.073
21-29 years	1917	47.8	1714	47.9	203	47.1		31	37.3		108	49.5		57	49.6
30-39 years	1629	40.6	1440	40.2	189	43.9		45	54.2		86	39.4		53	46.1
≥40 years	173	4.3	155	4.3	18	4.2		3	3.6		10	4.6		3	2.6
Missing	8	0.2	0	0.0	8	1.8		0	0.0		0	0.0		0	0.0
Onset of labor
Spontaneous	2611	64.9	2309	64.5	302	68.8	0.073	47	56.6	0.141	156	71.6	0.033	85	73.9	0.037
Induction	976	24.3	879	24.5	97	22.1	0.260	17	20.5	0.395	58	26.6	0.492	19	16.5	0.048
Elective caesarean section	512	12.7	462	12.9	50	11.5	0.371	11	13.3	0.924	28	12.8	0.982	10	8.7	0.184
Number of antenatal care visits
0	44	1.1	21	0.6	23	5.2	<0.001	10	12.0	<0.001	3	1.4	0.005	4	3.5	<0.001
1 to 3	238	5.9	201	5.6	37	8.4		6	7.2		18	8.3		12	10.4
4 to 8	2512	62.5	2225	62.1	287	65.4		53	63.9		150	68.8		73	63.5
More than 8	1226	30.5	1134	31.7	92	21.0		14	16.9		47	21.6		26	22.6
Missing	1	0.0	1	0.0	0	0.0		0	0.0		0	0.0		0	0.0

 

The citizenship of 23 women was not recorded and therefore they do not fall under the HDI classification. However they were analyzed under the category "migrant women".

p-values are for comparison of each group of migrant women with the group of Icelandic women, x2

Table II. Prevalence of singleton premature births in Iceland during 1997-2018.

	Total (n=89170)		Icelandic (n=81350)		Migrant (n=7820)			High HDI ≥0.900 (n=1771)			Middle HDI 0.850-0.899 (n=3928)			Low HDI ≤0.849 (n=1796)
	n	%	n	%	n	%	p	n	%	p	n	%	p	n	%	p
Preterm birth total	4021	4.5	3582	4.4	439	5.6	<0.001	83	4.7	0.565	218	5.5	0.001	115	6.4	<0.001
Missing	3558	3.9	2895	3.4	338	4.1		76	4.1		147	3.6		90	4.8
Extremely preterm <28 weeks	276	0.3	243	0.3	33	0.4	0.061	6	0.3	0.760	16	0.4	0.227	9	0.5	0.123
Very preterm 28w0d-31w6d	397	0.4	355	0.4	42	0.5	0.218	9	0.5	0.666	19	0.5	0.667	11	0.6	0.285
Moderate to late preterm 32w0d-36w6d	3348	3.8	2984	3.7	364	4.7	<0.001	68	3.8	0.704	183	4.7	0.001	95	5.3	<0.001

 

 

 

Table III. Prevalence of risk factors in women who gave birth to a singleton prematurely in Iceland during 1997-2018.

	Total (n=4021)		Icelandic (n=3582)		Migrant (n=439)			High HDI ≥0.900 (n=83)			Middle HDI 0.850-0.899 (n=218)			Low HDI ≤0.849 (n=115)
	n	%	n	%	n	%	p	n	%	p	n	%	p	n	%	p
Urinary tract infectionᵃ	6	0.1	4	0.1	2	0.5	0.133	0	0.0	1.000	2	0.9	0.042	0	0.0	1.000
Infection of amniotic sac and membraneᵃ	66	1.6	58	1.6	8	1.8	0.752	0	0.0	0.642	6	2.8	0.181	1	0.9	1.000
Sexually transmitted diseasesᵃ	14	0.3	13	0.4	1	0.2	1.000	0	0.0	1.000	0	0.0	1.000	1	0.9	0.358
Cervical incompetenceᵃ	7	0.2	6	0.2	1	0.2	0.555	0	0.0	1.000	1	0.5	0.339	0	0.0	1.000
Preeclampsia	643	16.0	590	16.5	53	12.1	0.018	8	9.6	0.096	30	13.8	0.293	10	8.7	0.026
Hypertensionᵃ	159	4.0	149	4.2	10	2.3	0.056	1	1.2	0.261	8	3.7	0.724	1	0.9	0.09
Diabetes	348	8.7	301	8.4	47	10.7	0.105	4	4.8	0.243	23	10.6	0.270	19	16.5	0.002
Anemiaᵃ	88	2.2	84	2.3	4	0.9	0.053	1	1.2	1.000	1	0.5	0.092	2	1.7	1.000
Obesityᵃ	194	4.8	182	5.1	12	2.7	0.030	2	2.4	0.440	8	3.7	0.353	0	0	0.007
Placental disorder	246	6.1	226	6.3	20	4.6	0.148	6	7.2	0.734	6	2.8	0.033	7	6.1	0.923
In vitro fertilizationᵃ	71	1.8	63	1.8	8	1.8	0.924	2	2.4	0.659	4	1.8	0.793	2	1.7	1.000
Preterm labor without deliveryᵃ	71	1.8	63	1.8	8	1.8	0.924	2	2.4	0.659	4	1.8	0.793	2	1.7	1.000
Premature rupture of membranes	1124	28.0	977	27.3	147	33.5	0.006	30	36.1	0.074	73	33.5	0.046	40	34.8	0.076
Mental disordersᵃ	42	1.0	42	1.2	0	0.0	0.012	0	0.0	1.000	0	0.0	0.172	0	0.0	0.641
Polyhydroamnionᵃ	107	2.7	96	2.7	11	2.5	0.830	2	2.4	1.000	4	1.8	0.449	5	4.3	0.244
Low birth weight	484	12.0	422	11.8	62	14.1	0.155	11	13.3	0.681	36	16.5	0.037	12	10.4	0.659
Supervision of high-risk pregnancyᵃ	100	2.5	93	2.6	7	1.6	0.203	1	1.2	0.724	3	1.4	0.265	3	2.6	1.000
Substance abuse	11	0.3	11	0.3	0	0.0	0.622	0	0.0	1.000	0	0.0	1.000	0	0.0	1.000
Liver and biliary tract disordersᵃ	86	2.1	77	2.1	9	2.1	0.892	0	0.0	0.421	5	2.3	0.810	4	3.5	0.319
Fetal stress	460	11.4	409	11.4	51	11.6	0.902	9	10.8	0.871	32	14.7	0.144	9	7.8	0.231
Stillbirthᵃ	182	4.5	164	4.6	18	4.1	0.649	4	4.8	0.791	8	3.7	0.531	5	4.3	0.907
Maternal age <18 yearsᵃ	41	1.0	41	1.1	0	0.0	0.019	0	0.0	1.000	0	0.0	0.170	0	0.0	0.638
Maternal age >40 yearsᵃ	122	3.0	110	3.1	12	2.7	0.697	3	3.6	0.742	5	2.3	0.515	3	2.6	0.319

The citizenship of 23 women was not recorded and therefore they do not fall under the HDI classification. However, they were analyzed under the category "migrant women".

ᵃ If Chi-square tests were not valid due to >20% cells having an expected cound <5, the Fisher exact test was used