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Published in: BMC Pregnancy and Childbirth 1/2013

Open Access 01-12-2013 | Research article

Retracted: Folic acid supplementation, dietary folate intake during pregnancy and risk for spontaneous preterm delivery: a prospective observational cohort study

Authors: Verena Sengpiel, Jonas Bacelis, Ronny Myhre, Solveig Myking, Aase Devold Pay, Margaretha Haugen, Anne-Lise Brantsæter, Helle Margrete Meltzer, Roy M Nilsen, Per Magnus, Stein Emil Vollset, Staffan Nilsson, Bo Jacobsson

Published in: BMC Pregnancy and Childbirth | Issue 1/2013

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Abstract

Background

Health authorities in numerous countries recommend periconceptional folic acid to pregnant women to prevent neural tube defects. The objective of this study was to examine the association of folic acid supplementation during different periods of pregnancy and of dietary folate intake with the risk of spontaneous preterm delivery (PTD).

Methods

The Norwegian Mother and Child Cohort Study is a population-based prospective cohort study. A total of 65,668 women with singleton pregnancies resulting in live births in 1999–2009 were included. Folic acid supplementation was self-reported from 26 weeks before pregnancy until week 24 during pregnancy. At gestational week 22, the women completed a food frequency questionnaire, which allowed the calculation of their average total folate intake from foods and supplements for the first 4–5 months of pregnancy. Spontaneous PTD was defined as the spontaneous onset of delivery between weeks 22+0 and 36+6 (n = 1,628).

Results

The median total folate intake was 266 μg/d (interquartile range IQR 154–543) in the overall population and 540 μg/d (IQR 369–651) in the supplement users. Eighty-three percent reported any folic acid supplementation from <8 weeks before to 24 weeks after conception while 42% initiated folic acid supplementation before their pregnancy. Cox regression analysis showed that the amount of folate intake from the diet (hazard ratio HR 1.16; confidence interval CI 0.65-2.08) and from the folic acid supplements (HR 1.04; CI 0.95-1.13) was not significantly associated with the risk of PTD. The initiation of folic acid supplementation more than 8 weeks before conception was associated with an increased risk for PTD (HR 1.19; CI 1.05-1.34) compared to no folic acid supplementation pre-conception. There was no significant association with PTD when supplementation was initiated within 8 weeks pre-conception (HR 1.01; CI 0.88-1.16). All analyses were adjusted for maternal characteristics and socioeconomic, health and dietary variables.

Conclusions

Our findings do not support a protective effect of dietary folate intake or folic acid supplementation on spontaneous PTD. Pre-conceptional folic acid supplementation starting more than 8 weeks before conception was associated with an increased risk of PTD. These results require further investigation before discussing an expansion of folic acid supplementation guidelines.
Appendix
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Literature
1.
go back to reference Tamura T, Picciano MF: Folate and human reproduction. Am J Clin Nutr. 2006, 83: 993-1016.PubMed Tamura T, Picciano MF: Folate and human reproduction. Am J Clin Nutr. 2006, 83: 993-1016.PubMed
2.
go back to reference Nordic Council of Ministers: Folate. Nordic Nutrition Recommendations 2004 Integrating nutrition and physical activity. 2004, Copenhagen: Norden, 287-296. Nordic Council of Ministers: Folate. Nordic Nutrition Recommendations 2004 Integrating nutrition and physical activity. 2004, Copenhagen: Norden, 287-296.
3.
go back to reference World Health Organization; Food and Agricultural Organization of the United Nations: Folate and Folic acid. Vitamin and mineral requirements in human nutrition. 2004, Rome: FAO, 53-62. World Health Organization; Food and Agricultural Organization of the United Nations: Folate and Folic acid. Vitamin and mineral requirements in human nutrition. 2004, Rome: FAO, 53-62.
4.
go back to reference Scholl TO, Johnson WG: Folic acid: influence on the outcome of pregnancy. Am J Clin Nutr. 2000, 71 (5 Suppl): 1295S-1303S.PubMed Scholl TO, Johnson WG: Folic acid: influence on the outcome of pregnancy. Am J Clin Nutr. 2000, 71 (5 Suppl): 1295S-1303S.PubMed
6.
go back to reference Czeizel AE, Dudas I, Metneki J: Pregnancy outcomes in a randomised controlled trial of periconceptional multivitamin supplementation. Final report. Arch Gynecol Obstet. 1994, 255: 131-139.CrossRefPubMed Czeizel AE, Dudas I, Metneki J: Pregnancy outcomes in a randomised controlled trial of periconceptional multivitamin supplementation. Final report. Arch Gynecol Obstet. 1994, 255: 131-139.CrossRefPubMed
7.
go back to reference Czeizel AE, Dudas I: Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. The New England journal of medicine. 1992, 327: 1832-1835.CrossRefPubMed Czeizel AE, Dudas I: Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. The New England journal of medicine. 1992, 327: 1832-1835.CrossRefPubMed
8.
go back to reference MRC Vitamin Study Research Group: Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet. 1991, 338: 131-137.CrossRef MRC Vitamin Study Research Group: Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet. 1991, 338: 131-137.CrossRef
9.
go back to reference Shaw GM, Carmichael SL, Nelson V, Selvin S, Schaffer DM: Occurrence of low birthweight and preterm delivery among California infants before and after compulsory food fortification with folic acid. Public Health Rep. 2004, 119: 170-173.PubMedPubMedCentral Shaw GM, Carmichael SL, Nelson V, Selvin S, Schaffer DM: Occurrence of low birthweight and preterm delivery among California infants before and after compulsory food fortification with folic acid. Public Health Rep. 2004, 119: 170-173.PubMedPubMedCentral
10.
go back to reference de Bree A, van Dusseldorp M, Brouwer IA, van het Hof KH, Steegers-Theunissen RP: Folate intake in Europe: recommended, actual and desired intake. Eur J Clin Nutr. 1997, 51: 643-660.CrossRefPubMed de Bree A, van Dusseldorp M, Brouwer IA, van het Hof KH, Steegers-Theunissen RP: Folate intake in Europe: recommended, actual and desired intake. Eur J Clin Nutr. 1997, 51: 643-660.CrossRefPubMed
12.
go back to reference WHO Expert Committee: The prevention of perinatal mortality and morbidity. Report of a WHO Expert Committee. World Health Organ Tech Rep Ser. 1970, 457: 1-60. WHO Expert Committee: The prevention of perinatal mortality and morbidity. Report of a WHO Expert Committee. World Health Organ Tech Rep Ser. 1970, 457: 1-60.
13.
go back to reference Moster D, Lie RT, Markestad T: Long-term medical and social consequences of preterm birth. N Engl J Med. 2008, 359: 262-273.CrossRefPubMed Moster D, Lie RT, Markestad T: Long-term medical and social consequences of preterm birth. N Engl J Med. 2008, 359: 262-273.CrossRefPubMed
14.
go back to reference Bryce J, Boschi-Pinto C, Shibuya K, Black RE: WHO estimates of the causes of death in children. Lancet. 2005, 365: 1147-1152.CrossRefPubMed Bryce J, Boschi-Pinto C, Shibuya K, Black RE: WHO estimates of the causes of death in children. Lancet. 2005, 365: 1147-1152.CrossRefPubMed
15.
go back to reference Magnus P, Irgens LM, Haug K, Nystad W, Skjaerven R, Stoltenberg C: Cohort profile: the Norwegian Mother and Child Cohort Study (MoBa). Int J Epidemiol. 2006, 35: 1146-1150.CrossRefPubMed Magnus P, Irgens LM, Haug K, Nystad W, Skjaerven R, Stoltenberg C: Cohort profile: the Norwegian Mother and Child Cohort Study (MoBa). Int J Epidemiol. 2006, 35: 1146-1150.CrossRefPubMed
16.
17.
go back to reference Hassan SS, Romero R, Vidyadhari D, Fusey S, Baxter JK, Khandelwal M, Vijayaraghavan J, Trivedi Y, Soma-Pillay P, Sambarey P, Dayal A, Potapov V, O'Brien J, Astakhov V, Yuzko O, Kinzler W, Dattel B, Sehdev H, Mazheika L, Manchulenko D, Gervasi MT, Sullivan L, Conde-Agudelo A, Phillips JA, Creasy GW: Vaginal progesterone reduces the rate of preterm birth in women with a sonographic short cervix: a multicenter, randomized, double-blind, placebo-controlled trial. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 2011, 38: 18-31.CrossRef Hassan SS, Romero R, Vidyadhari D, Fusey S, Baxter JK, Khandelwal M, Vijayaraghavan J, Trivedi Y, Soma-Pillay P, Sambarey P, Dayal A, Potapov V, O'Brien J, Astakhov V, Yuzko O, Kinzler W, Dattel B, Sehdev H, Mazheika L, Manchulenko D, Gervasi MT, Sullivan L, Conde-Agudelo A, Phillips JA, Creasy GW: Vaginal progesterone reduces the rate of preterm birth in women with a sonographic short cervix: a multicenter, randomized, double-blind, placebo-controlled trial. Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 2011, 38: 18-31.CrossRef
18.
go back to reference Dodd JM, Flenady VJ, Cincotta R, Crowther CA: Progesterone for the prevention of preterm birth: a systematic review. Obstet Gynecol. 2008, 112: 127-134.CrossRefPubMed Dodd JM, Flenady VJ, Cincotta R, Crowther CA: Progesterone for the prevention of preterm birth: a systematic review. Obstet Gynecol. 2008, 112: 127-134.CrossRefPubMed
19.
go back to reference Romero R, Nicolaides K, Conde-Agudelo A, Tabor A, O'Brien JM, Cetingoz E, Da Fonseca E, Creasy GW, Klein K, Rode L, Soma-Pillay P, Fusey S, Cam C, Alfirevic Z, Hassan SS: Vaginal progesterone in women with an asymptomatic sonographic short cervix in the midtrimester decreases preterm delivery and neonatal morbidity: a systematic review and metaanalysis of individual patient data. American journal of obstetrics and gynecology. 2012, 206: 124-e121-119CrossRefPubMed Romero R, Nicolaides K, Conde-Agudelo A, Tabor A, O'Brien JM, Cetingoz E, Da Fonseca E, Creasy GW, Klein K, Rode L, Soma-Pillay P, Fusey S, Cam C, Alfirevic Z, Hassan SS: Vaginal progesterone in women with an asymptomatic sonographic short cervix in the midtrimester decreases preterm delivery and neonatal morbidity: a systematic review and metaanalysis of individual patient data. American journal of obstetrics and gynecology. 2012, 206: 124-e121-119CrossRefPubMed
20.
go back to reference Papadopoulou E, Stratakis N, Roumeliotaki T, Sarri K, Merlo DF, Kogevinas M, Chatzi L: The effect of high doses of folic acid and iron supplementation in early-to-mid pregnancy on prematurity and fetal growth retardation: the mother-child cohort study in Crete, Greece (Rhea study). European journal of nutrition. 2013, 52: 327-336.CrossRefPubMed Papadopoulou E, Stratakis N, Roumeliotaki T, Sarri K, Merlo DF, Kogevinas M, Chatzi L: The effect of high doses of folic acid and iron supplementation in early-to-mid pregnancy on prematurity and fetal growth retardation: the mother-child cohort study in Crete, Greece (Rhea study). European journal of nutrition. 2013, 52: 327-336.CrossRefPubMed
21.
go back to reference Bukowski R, Malone FD, Porter FT, Nyberg DA, Comstock CH, Hankins GD, Eddleman K, Gross SJ, Dugoff L, Craigo SD, Timor-Tritsch IE, Carr SR, Wolfe HM, D'Alton ME: Preconceptional folate supplementation and the risk of spontaneous preterm birth: a cohort study. PLoS Med. 2009, 6: e1000061-CrossRefPubMedPubMedCentral Bukowski R, Malone FD, Porter FT, Nyberg DA, Comstock CH, Hankins GD, Eddleman K, Gross SJ, Dugoff L, Craigo SD, Timor-Tritsch IE, Carr SR, Wolfe HM, D'Alton ME: Preconceptional folate supplementation and the risk of spontaneous preterm birth: a cohort study. PLoS Med. 2009, 6: e1000061-CrossRefPubMedPubMedCentral
22.
go back to reference Czeizel AE, Puho EH, Langmar Z, Acs N, Banhidy F: Possible association of folic acid supplementation during pregnancy with reduction of preterm birth: a population-based study. European journal of obstetrics, gynecology, and reproductive biology. 2010, 148: 135-140.CrossRefPubMed Czeizel AE, Puho EH, Langmar Z, Acs N, Banhidy F: Possible association of folic acid supplementation during pregnancy with reduction of preterm birth: a population-based study. European journal of obstetrics, gynecology, and reproductive biology. 2010, 148: 135-140.CrossRefPubMed
23.
go back to reference Charles DH, Ness AR, Campbell D, Smith GD, Whitley E, Hall MH: Folic acid supplements in pregnancy and birth outcome: re-analysis of a large randomised controlled trial and update of Cochrane review. Paediatr Perinat Epidemiol. 2005, 19: 112-124.CrossRefPubMed Charles DH, Ness AR, Campbell D, Smith GD, Whitley E, Hall MH: Folic acid supplements in pregnancy and birth outcome: re-analysis of a large randomised controlled trial and update of Cochrane review. Paediatr Perinat Epidemiol. 2005, 19: 112-124.CrossRefPubMed
24.
go back to reference Fekete K, Berti C, Trovato M, Lohner S, Dullemeijer C, Souverein OW, Cetin I, Decsi T: Effect of folate intake on health outcomes in pregnancy: a systematic review and meta-analysis on birth weight, placental weight and length of gestation. Nutrition journal. 2012, 11: 75-CrossRefPubMedPubMedCentral Fekete K, Berti C, Trovato M, Lohner S, Dullemeijer C, Souverein OW, Cetin I, Decsi T: Effect of folate intake on health outcomes in pregnancy: a systematic review and meta-analysis on birth weight, placental weight and length of gestation. Nutrition journal. 2012, 11: 75-CrossRefPubMedPubMedCentral
25.
go back to reference Pennell CE, Jacobsson B, Williams SM, Buus RM, Muglia LJ, Dolan SM, Morken NH, Ozcelik H, Lye SJ, Relton C: Genetic epidemiologic studies of preterm birth: guidelines for research. American journal of obstetrics and gynecology. 2007, 196: 107-118.CrossRefPubMed Pennell CE, Jacobsson B, Williams SM, Buus RM, Muglia LJ, Dolan SM, Morken NH, Ozcelik H, Lye SJ, Relton C: Genetic epidemiologic studies of preterm birth: guidelines for research. American journal of obstetrics and gynecology. 2007, 196: 107-118.CrossRefPubMed
27.
go back to reference Irgens LM: The Medical Birth Registry of Norway. Epidemiological research and surveillance throughout 30 years. Acta Obstet Gynecol Scand. 2000, 79: 435-439.CrossRefPubMed Irgens LM: The Medical Birth Registry of Norway. Epidemiological research and surveillance throughout 30 years. Acta Obstet Gynecol Scand. 2000, 79: 435-439.CrossRefPubMed
28.
go back to reference Meltzer HM, Brantsaeter AL, Ydersbond TA, Alexander J, Haugen M: Methodological challenges when monitoring the diet of pregnant women in a large study: experiences from the Norwegian Mother and Child Cohort Study (MoBa). Matern Child Nutr. 2008, 4: 14-27.CrossRefPubMed Meltzer HM, Brantsaeter AL, Ydersbond TA, Alexander J, Haugen M: Methodological challenges when monitoring the diet of pregnant women in a large study: experiences from the Norwegian Mother and Child Cohort Study (MoBa). Matern Child Nutr. 2008, 4: 14-27.CrossRefPubMed
31.
go back to reference Brantsaeter AL, Haugen M, Hagve TA, Aksnes L, Rasmussen SE, Julshamn K, Alexander J, Meltzer HM: Self-reported dietary supplement use is confirmed by biological markers in the Norwegian Mother and Child Cohort Study (MoBa). Ann Nutr Metab. 2007, 51: 146-154.CrossRefPubMed Brantsaeter AL, Haugen M, Hagve TA, Aksnes L, Rasmussen SE, Julshamn K, Alexander J, Meltzer HM: Self-reported dietary supplement use is confirmed by biological markers in the Norwegian Mother and Child Cohort Study (MoBa). Ann Nutr Metab. 2007, 51: 146-154.CrossRefPubMed
32.
go back to reference Haugen M, Brantsaeter AL, Alexander J, Meltzer HM: Dietary supplements contribute substantially to the total nutrient intake in pregnant Norwegian women. Ann Nutr Metab. 2008, 52: 272-280.CrossRefPubMedPubMedCentral Haugen M, Brantsaeter AL, Alexander J, Meltzer HM: Dietary supplements contribute substantially to the total nutrient intake in pregnant Norwegian women. Ann Nutr Metab. 2008, 52: 272-280.CrossRefPubMedPubMedCentral
33.
go back to reference FAO/WHO Expert Consultation: Requirements of Vitamin A, Iron, Folate and Vitamin B12 Report of a Joint FAO/WHO Expert Consultation (FAO Fisheries Report). World Health Organization, . 1988, Rome FAO/WHO Expert Consultation: Requirements of Vitamin A, Iron, Folate and Vitamin B12 Report of a Joint FAO/WHO Expert Consultation (FAO Fisheries Report). World Health Organization, . 1988, Rome
34.
go back to reference Grambsch PM, Therneau TM: Proportional hazards tests and diagnostics based on weighted residuals. Biometrika. 1994, 81: 515-526.CrossRef Grambsch PM, Therneau TM: Proportional hazards tests and diagnostics based on weighted residuals. Biometrika. 1994, 81: 515-526.CrossRef
35.
36.
go back to reference Alwan NA, Greenwood DC, Simpson NA, McArdle HJ, Cade JE: The relationship between dietary supplement use in late pregnancy and birth outcomes: a cohort study in British women. BJOG : an international journal of obstetrics and gynaecology. 2010, 117: 821-829.CrossRef Alwan NA, Greenwood DC, Simpson NA, McArdle HJ, Cade JE: The relationship between dietary supplement use in late pregnancy and birth outcomes: a cohort study in British women. BJOG : an international journal of obstetrics and gynaecology. 2010, 117: 821-829.CrossRef
37.
go back to reference Catov JM, Bodnar LM, Olsen J, Olsen S, Nohr EA: Periconceptional multivitamin use and risk of preterm or small-for-gestational-age births in the Danish National Birth Cohort. The American journal of clinical nutrition. 2011, 94: 906-912.CrossRefPubMedPubMedCentral Catov JM, Bodnar LM, Olsen J, Olsen S, Nohr EA: Periconceptional multivitamin use and risk of preterm or small-for-gestational-age births in the Danish National Birth Cohort. The American journal of clinical nutrition. 2011, 94: 906-912.CrossRefPubMedPubMedCentral
38.
go back to reference Nilsen RM, Vollset SE, Monsen AL, Ulvik A, Haugen M, Meltzer HM, Magnus P, Ueland PM: Infant birth size is not associated with maternal intake and status of folate during the second trimester in Norwegian pregnant women. The Journal of nutrition. 2010, 140: 572-579.CrossRefPubMed Nilsen RM, Vollset SE, Monsen AL, Ulvik A, Haugen M, Meltzer HM, Magnus P, Ueland PM: Infant birth size is not associated with maternal intake and status of folate during the second trimester in Norwegian pregnant women. The Journal of nutrition. 2010, 140: 572-579.CrossRefPubMed
39.
go back to reference Timmermans S, Jaddoe VW, Hofman A, Steegers-Theunissen RP, Steegers EA: Periconception folic acid supplementation, fetal growth and the risks of low birth weight and preterm birth: the Generation R Study. The British journal of nutrition. 2009, 102: 777-785.CrossRefPubMed Timmermans S, Jaddoe VW, Hofman A, Steegers-Theunissen RP, Steegers EA: Periconception folic acid supplementation, fetal growth and the risks of low birth weight and preterm birth: the Generation R Study. The British journal of nutrition. 2009, 102: 777-785.CrossRefPubMed
40.
go back to reference Dunlop AL, Taylor RN, Tangpricha V, Fortunato S, Menon R: Maternal Micronutrient Status and Preterm Versus Term Birth for Black and White US Women. Reproductive sciences. 2012, 19: 939-948.CrossRefPubMedPubMedCentral Dunlop AL, Taylor RN, Tangpricha V, Fortunato S, Menon R: Maternal Micronutrient Status and Preterm Versus Term Birth for Black and White US Women. Reproductive sciences. 2012, 19: 939-948.CrossRefPubMedPubMedCentral
41.
go back to reference Shaw GM, Carmichael SL, Yang W, Siega-Riz AM: Periconceptional intake of folic acid and food folate and risks of preterm delivery. American journal of perinatology. 2011, 28: 747-752.CrossRefPubMed Shaw GM, Carmichael SL, Yang W, Siega-Riz AM: Periconceptional intake of folic acid and food folate and risks of preterm delivery. American journal of perinatology. 2011, 28: 747-752.CrossRefPubMed
42.
go back to reference Fleming AF, Martin JD, Stenhouse NS: Pregnancy anaemia, iron and folate deficiency in Western Australia. Med J Aust. 1974, 2: 479-484.PubMed Fleming AF, Martin JD, Stenhouse NS: Pregnancy anaemia, iron and folate deficiency in Western Australia. Med J Aust. 1974, 2: 479-484.PubMed
43.
go back to reference Fletcher J, Gurr A, Fellingham FR, Prankerd TA, Brant HA, Menzies DN: The value of folic acid supplements in pregnancy. J Obstet Gynaecol Br Commonw. 1971, 78: 781-785.CrossRefPubMed Fletcher J, Gurr A, Fellingham FR, Prankerd TA, Brant HA, Menzies DN: The value of folic acid supplements in pregnancy. J Obstet Gynaecol Br Commonw. 1971, 78: 781-785.CrossRefPubMed
44.
45.
go back to reference Rolschau J, Kristoffersen K, Ulrich M, Grinsted P, Schaumburg E, Foged N: The influence of folic acid supplement on the outcome of pregnancies in the county of Funen in Denmark. Part I. Eur J Obstet Gynecol Reprod Biol. 1999, 87: 105-110. discussion 103–104CrossRefPubMed Rolschau J, Kristoffersen K, Ulrich M, Grinsted P, Schaumburg E, Foged N: The influence of folic acid supplement on the outcome of pregnancies in the county of Funen in Denmark. Part I. Eur J Obstet Gynecol Reprod Biol. 1999, 87: 105-110. discussion 103–104CrossRefPubMed
46.
go back to reference Scholl TO, Hediger ML, Bendich A, Schall JI, Smith WK, Krueger PM: Use of multivitamin/mineral prenatal supplements: influence on the outcome of pregnancy. Am J Epidemiol. 1997, 146: 134-141.CrossRefPubMed Scholl TO, Hediger ML, Bendich A, Schall JI, Smith WK, Krueger PM: Use of multivitamin/mineral prenatal supplements: influence on the outcome of pregnancy. Am J Epidemiol. 1997, 146: 134-141.CrossRefPubMed
47.
go back to reference Siega-Riz AM, Savitz DA, Zeisel SH, Thorp JM, Herring A: Second trimester folate status and preterm birth. Am J Obstet Gynecol. 2004, 191: 1851-1857.CrossRefPubMed Siega-Riz AM, Savitz DA, Zeisel SH, Thorp JM, Herring A: Second trimester folate status and preterm birth. Am J Obstet Gynecol. 2004, 191: 1851-1857.CrossRefPubMed
48.
go back to reference Furness DL, Yasin N, Dekker GA, Thompson SD, Roberts CT: Maternal red blood cell folate concentration at 10–12 weeks gestation and pregnancy outcome. The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians. 2012, 25: 1423-1427.CrossRef Furness DL, Yasin N, Dekker GA, Thompson SD, Roberts CT: Maternal red blood cell folate concentration at 10–12 weeks gestation and pregnancy outcome. The journal of maternal-fetal & neonatal medicine : the official journal of the European Association of Perinatal Medicine, the Federation of Asia and Oceania Perinatal Societies, the International Society of Perinatal Obstetricians. 2012, 25: 1423-1427.CrossRef
49.
go back to reference Scholl TO, Hediger ML, Schall JI, Khoo CS, Fischer RL: Dietary and serum folate: their influence on the outcome of pregnancy. Am J Clin Nutr. 1996, 63: 520-525.PubMed Scholl TO, Hediger ML, Schall JI, Khoo CS, Fischer RL: Dietary and serum folate: their influence on the outcome of pregnancy. Am J Clin Nutr. 1996, 63: 520-525.PubMed
50.
go back to reference Bailey RL, Dodd KW, Gahche JJ, Dwyer JT, McDowell MA, Yetley EA, Sempos CA, Burt VL, Radimer KL, Picciano MF: Total folate and folic acid intake from foods and dietary supplements in the United States: 2003–2006. The American journal of clinical nutrition. 2010, 91: 231-237.CrossRefPubMed Bailey RL, Dodd KW, Gahche JJ, Dwyer JT, McDowell MA, Yetley EA, Sempos CA, Burt VL, Radimer KL, Picciano MF: Total folate and folic acid intake from foods and dietary supplements in the United States: 2003–2006. The American journal of clinical nutrition. 2010, 91: 231-237.CrossRefPubMed
51.
go back to reference Nilsen RM, Vollset SE, Gjessing HK, Magnus P, Meltzer HM, Haugen M, Ueland PM: Patterns and predictors of folic acid supplement use among pregnant women: the Norwegian Mother and Child Cohort Study. Am J Clin Nutr. 2006, 84: 1134-1141.PubMed Nilsen RM, Vollset SE, Gjessing HK, Magnus P, Meltzer HM, Haugen M, Ueland PM: Patterns and predictors of folic acid supplement use among pregnant women: the Norwegian Mother and Child Cohort Study. Am J Clin Nutr. 2006, 84: 1134-1141.PubMed
52.
go back to reference Bergen NE, Jaddoe VW, Timmermans S, Hofman A, Lindemans J, Russcher H, Raat H, Steegers-Theunissen RP, Steegers EA: Homocysteine and folate concentrations in early pregnancy and the risk of adverse pregnancy outcomes: the Generation R Study. BJOG : an international journal of obstetrics and gynaecology. 2012, 119: 739-751.CrossRef Bergen NE, Jaddoe VW, Timmermans S, Hofman A, Lindemans J, Russcher H, Raat H, Steegers-Theunissen RP, Steegers EA: Homocysteine and folate concentrations in early pregnancy and the risk of adverse pregnancy outcomes: the Generation R Study. BJOG : an international journal of obstetrics and gynaecology. 2012, 119: 739-751.CrossRef
53.
go back to reference Nilsen RM, Vollset SE, Gjessing HK, Skjaerven R, Melve KK, Schreuder P, Alsaker ER, Haug K, Daltveit AK, Magnus P: Self-selection and bias in a large prospective pregnancy cohort in Norway. Paediatr Perinat Epidemiol. 2009, 23: 597-608.CrossRefPubMed Nilsen RM, Vollset SE, Gjessing HK, Skjaerven R, Melve KK, Schreuder P, Alsaker ER, Haug K, Daltveit AK, Magnus P: Self-selection and bias in a large prospective pregnancy cohort in Norway. Paediatr Perinat Epidemiol. 2009, 23: 597-608.CrossRefPubMed
54.
go back to reference Brantsaeter AL, Haugen M, Alexander J, Meltzer HM: Validity of a new food frequency questionnaire for pregnant women in the Norwegian Mother and Child Cohort Study (MoBa). Matern Child Nutr. 2008, 4: 28-43.CrossRefPubMed Brantsaeter AL, Haugen M, Alexander J, Meltzer HM: Validity of a new food frequency questionnaire for pregnant women in the Norwegian Mother and Child Cohort Study (MoBa). Matern Child Nutr. 2008, 4: 28-43.CrossRefPubMed
Metadata
Title
Retracted: Folic acid supplementation, dietary folate intake during pregnancy and risk for spontaneous preterm delivery: a prospective observational cohort study
Authors
Verena Sengpiel
Jonas Bacelis
Ronny Myhre
Solveig Myking
Aase Devold Pay
Margaretha Haugen
Anne-Lise Brantsæter
Helle Margrete Meltzer
Roy M Nilsen
Per Magnus
Stein Emil Vollset
Staffan Nilsson
Bo Jacobsson
Publication date
01-12-2013
Publisher
BioMed Central
Published in
BMC Pregnancy and Childbirth / Issue 1/2013
Electronic ISSN: 1471-2393
DOI
https://doi.org/10.1186/1471-2393-13-160

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