Plasma folate levels and risk of spontaneous abortion.
BACKGROUND
Both folate deficiency and folic acid supplements have been reported to increase the risk of spontaneous abortion. The results are inconclusive, however, and measurements of folate have not been available in all studies.


OBJECTIVE
To study the association between plasma folate levels and the risk of spontaneous abortion.


METHODS
Population-based, matched, case-control study of case women with spontaneous abortion and control women from January 1996 through December 1998 in Uppsala County, Sweden. Plasma folate measurements were available for 468 cases and 921 controls at 6 to 12 gestational weeks.


METHODS
Risk of spontaneous abortion vs maternal plasma folate level.


RESULTS
Compared with women with plasma folate levels between 2.20 and 3.95 ng/mL (5.0 and 8.9 nmol/L), women with low (< or =2.19 ng/mL [< or =4.9 nmol/L]) folate levels were at increased risk of spontaneous abortion (adjusted odds ratio [OR], 1.47; 95% confidence interval [CI], 1.01-2.14), whereas women with higher folate levels (3.96-6.16 ng/mL [9.0-13.9 nmol/L] and > or =6.17 ng/mL [> or =14.0 nmol/L]) showed no increased risk of spontaneous abortion (OR, 0.84; 95% CI, 0.59-1.20; and OR, 0.74; 95% CI, 0.47-1.16, respectively). Low folate levels were associated with a significantly increased risk when the fetal karyotype was abnormal (OR, 1.95; 95% CI, 1.09-3.48) but not when the fetal karyotype was normal (OR, 1.11; 95% CI, 0.55-2.24) or unknown (OR, 1.45; 95% CI, 0.90-2.33).


CONCLUSIONS
Low plasma folate levels were associated with an increased risk of early spontaneous abortion.
George
Lena
L
Department of Medical Epidemiology, Huddinge University Hospital, Karolinska Institutet, PO Box 281, SE-171 77 Stockholm, Sweden.
Mills
James L
JL
Johansson
Anna L V
AL
Nordmark
Anna
A
Olander
Bodil
B
Granath
Fredrik
F
Cnattingius
Sven
S
D000022:Abortion, Spontaneous / Q000097:blood / Q000453:epidemiology* / Q000209:etiology*; D016022:Case-Control Studies; D019587:Dietary Supplements; D005260:Female; D005315:Fetal Diseases / Q000235:genetics; D005333:Fetus / Q000166:cytology; D005492:Folic Acid / Q000097:blood*; D005494:Folic Acid Deficiency / Q000150:complications*; D005865:Gestational Age; D006801:Humans; D007621:Karyotyping; D016015:Logistic Models; D008297:Male; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology
D005492:Folic Acid