Risk of placental dysfunction disorders after prior miscarriages: a population-based study.
OBJECTIVE
The objective of the investigation was to study the association between prior miscarriages and the risks of placental dysfunction disorders, including preeclampsia, stillbirth, birth of a small for gestational age (SGA) infant, placental abruption, and spontaneous preterm birth.


METHODS
In a population-based cohort study including 619,587 primiparous women, we estimated risks of placental dysfunction disorders for women with 1 (n = 68,185), 2 (n = 11,410) and 3 or more (n = 3823) self-reported prior miscarriages. Risks were calculated as odds ratios by unconditional logistic regression analysis and adjustments were made for maternal age, early pregnancy body mass index, height, smoking habits, country of birth, years of formal education, in vitro fertilization, chronic hypertension, pregestational diabetes, hypothyroidism, systemic lupus erythematosis, fetal sex, and year of childbirth.


RESULTS
Compared with women with no prior miscarriage, women with 1 prior miscarriage had almost no increased risks. Women with 2 prior miscarriages had increased risks of spontaneous preterm birth, preterm (<37 weeks) SGA infant, and placental abruption. The rates of all disorders were higher for women with 3 or more prior miscarriages compared with women without prior miscarriages: preeclampsia, 5.83% vs 4.27%; stillbirth, 0.69% vs 0.33%, SGA infant, 5.09% vs 3.22%, placental abruption, 0.81% vs 0.41%; and spontaneous preterm birth, 6.45% vs 4.40%. The adjusted odds ratios for preterm (<37 weeks) disorders in women with 3 prior miscarriages were approximately 2.


CONCLUSIONS
History of 2 or more miscarriages is associated with an increased risk of placental dysfunction disorders and should be regarded as a risk factor in antenatal care.
Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden. Electronic address: johanna.gunnarsdottir@kbh.uu.se.
Johanna
J
Gunnarsdottir
Clinical Epidemiology Unit, Department of Medicine, Karolinska Institute, Stockholm, Sweden; Division of Obstetrics and Gynecology, Department of Women's and Children's Health, Karolinska University Hospital and Institute, Stockholm, Sweden.
Olof
O
Stephansson
Clinical Epidemiology Unit, Department of Medicine, Karolinska Institute, Stockholm, Sweden.
Sven
S
Cnattingius
Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden.
Helena
H
Akerud
Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden; Clinical Epidemiology Unit, Department of Medicine, Karolinska Institute, Stockholm, Sweden.
Anna-Karin
AK
Wikström
D000022:Abortion, Spontaneous; D000328:Adult; D015331:Cohort Studies; D005260:Female; D005317:Fetal Growth Retardation / Q000209:etiology; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D016015:Logistic Models; D016017:Odds Ratio; D010298:Parity; D010922:Placenta Diseases / Q000209:etiology*; D011225:Pre-Eclampsia / Q000209:etiology; D011247:Pregnancy; D047928:Premature Birth / Q000209:etiology; D012042:Registries; D012307:Risk Factors; D057566:Self Report; D050497:Stillbirth
intrauterine growth restriction; miscarriage; placental abruption; preeclampsia; spontaneous preterm birth; stillbirth