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Vitamin D Status during Pregnancy: a Longitudinal Study in Swedish Women from Early Pregnancy to Seven Months Postpartum
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Family Medicine.ORCID iD: 0000-003-1730-699X
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Family Medicine.
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
Umeå University, Faculty of Medicine, Department of Odontology.
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2016 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, no 3, e0150385Article in journal (Refereed) Published
Abstract [en]

Low vitamin D levels during pregnancy may have negative consequences for the health of both the mother and child. Cross-sectional studies in childbearing women suggest that vitamin D levels are low during pregnancy, but few studies have followed the same women during pregnancy and postpartum. The aims of this study were to longitudinally assess vitamin D status during pregnancy and postpartum and identify the factors associated with vitamin D status in pregnant women in northern Sweden. Between September 2006 and March 2009, 184 women were consecutively recruited at five antenatal primary care clinics. Blood was sampled, and dietary intake was estimated using a food frequency questionnaire with 66 food items/food aggregates and questions on the intake of vitamin supplements at gestational weeks 12, 21, and 35, as well as at 12 and 29 weeks after birth. Plasma 25(OH) vitamin D levels were analyzed using liquid chromatography tandem-mass spectrometry. At least one-third of the women had 25(OH) vitamin D levels <50 nmol/L on at least one sampling occasion. Plasma levels increased slightly over the gestation period and peaked in late pregnancy. The levels reverted to the baseline levels after birth. Multivariate analysis showed that gestational and postpartum week, season, dietary intake of vitamin D, and vitamin supplementation were significantly related to plasma levels. There was also an influence of season on the longitudinal concentration patterns. In conclusion, more than one-third of the women studied had low 25(OH) vitamin D levels, and gestational and postpartum week was related to 25(OH) vitamin D levels after adjustment for season and vitamin D intake.

Place, publisher, year, edition, pages
2016. Vol. 11, no 3, e0150385
National Category
Family Medicine Obstetrics, Gynecology and Reproductive Medicine
URN: urn:nbn:se:umu:diva-117426DOI: 10.1371/journal.pone.0150385ISI: 000371735200077OAI: diva2:907479
Available from: 2016-02-29 Created: 2016-02-29 Last updated: 2016-05-16Bibliographically approved
In thesis
1. Nutritional aspects of behaviour and biology during pregnancy and postpartum
Open this publication in new window or tab >>Nutritional aspects of behaviour and biology during pregnancy and postpartum
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]


A well-balanced nutritious diet is important for the pregnant woman and the growing fetus, as well as for their future health. Poor nutrition results from both over-consumption of energy-rich foods which can lead to a higher weight gain than is healthy and under-nutrition of essential nutrients. Food intake is regulated in complex biological systems by many factors, where steroid hormone is one factor involved.

The overall aim of this thesis is to describe dietary intake, vitamin D levels, dietary information and dietary changes, and to study the relation between allopregnanolone and weight gain during pregnancy and postpartum.


Study I was a qualitative study with focus group interviews with 23 pregnant women. The text was analysed with content analysis. Study II was a quantitative cross-sectional study conducted in early pregnancy (n=209) with a reference group (n=206). Self-reported dietary data from a questionnaire was analysed using descriptive comparative statistics and a cluster analysis model (Partial Least Squares modelling). Study III had a quantitative longitudinal design. Vitamin D concentrations were analysed in 184 women, collected on five occasions during pregnancy and postpartum. Descriptive comparative statistics and a linear mixed model were used. Study IV was a quantitative longitudinal study with 60 women. Concentrations of allopregnanolone were analysed in gestational week 12 and 35. Descriptive and comparative statistics as well as Spearman’s correlation (rho) were used to describe the relationship between weight gain and allopregnanolone concentrations.



The focus group interviews showed that women wanted to know more about different foods to reduce any risk for their child but the information about foods was partly up to themselves to find out. They expressedfeelingsof insecurityand guiltif they accidentallyate something“forbidden”. The recommendationswere followedas best as possiblealong withcommon sense todeal with dietchanges. The main themes were “Finding out by oneself”, “Getting professional advice when health problems occur”, “Being uncertain” and “Being responsible with a pinch of salt”. Some differences in the dietary patterns were found among the pregnant women compared to references, with less, vegetables (47 g/day), potatoes/rice/pasta (31 g/day), meat/fish (24 g/day) and intake of alcohol and tobacco/snuff but a higher intake of supplements. Bothpregnant women and referenceshad intakes offolatethrough diet45% (pregnant) and 22% (references) lower than current recommendations(500vs400g/day). Vitamin Dintake was34% lower than the recommendationsof 10mg/day. At least a third of the participants had insufficient plasma levels below 50 nmol/L of vitamin D. Season was a strong factor influencing the longitudinal pattern. Gestational week, season, total energy intake, dietary intake of vitamin D, and multivitamin supplementation over the previous 14 days were factors related to vitamin D levels. A correlation betweenallopregnanoloneconcentrations ingestationalweek 35and weight gainin weeks12–35was seen (p = 0.016). Therewas alsoa correlation betweenthe increase inallopregnanolone(weeks12–35) andweight gain(see above) (p = 0.028).



Dietary recommendations were described as contradictory and confusing and the dietary advice felt inadequate. The women faced their diet changes and sought information on their own but would have wished for more extensive advice from the midwife. The intake of vitamins essential for pregnancy was lower than recommended, which is also confirmed by low plasma levels of vitamin D in at least one third of the pregnant women. Vitamin D levels peaked in late pregnancy. Aside from gestational week and season which were related to plasma levels, intake from foods and supplements also affected the levels. Reasons for weight gain are complex and depend on many factors. Allopregnanolone is a factor that was seen to relate to the weight gain of the studied pregnant women.

Abstract [sv]


En välbalanserad näringsrik kost är viktig för den gravida kvinnan och det växande fostret, så även för deras framtida hälsa. En bristfällig kost kan utgöras av både överförbrukning av energirika livsmedel vilket kan leda till högre viktuppgång än vad som är hälsosamt och bristande intag av viktiga näringsämnen. Kostintag regleras av komplexa biologiska system där flera faktorer är inblandade däribland steroidhormonet allopregnanolon. Det övergripande syftet med denna avhandling är att under och efter graviditet beskriva kostintag, vitamin D-nivåer, kostinformation och kostförändringar och att studera allopregnanolons relation till viktökning.


Studie I var en kvalitativ studie med fokusgruppsintervjuer med 23 gravida kvinnor. Texten analyserades med innehållsanalys. Studie II var en kvantitativ tvärsnittsstudie som genomfördes i tidig graviditet (n = 209) och med en grupp icke-gravida kvinnor (kontrollgrupp) (n=206). Självrapporterade kostdata från ett frågeformulär analyserades med beskrivande, jämförande statistik och en klusteranalysmodell (Partial Least Squares modellering). Studie III hade en kvantitativ longitudinell design. Vitamin D-koncentrationer analyserades hos 184 kvinnor, vid fem tillfällen under graviditeten och efter förlossningen. Beskrivande, jämförande statistik och en linjär mixad regressionsmodell användes. Studie IV var en kvantitativ longitudinell studie med 60 kvinnor. Koncentrationerna av allopregnanolon analyserades vid graviditetsvecka 12 och 35. Beskrivande och jämförande statistik samt Spearman’s korrelation användes för att beskriva samband mellan viktökning och koncentrationer av allopregnanolon.


Intervjuerna i studie I visade att kvinnor ville veta mer om olika typer av mat för att minska en eventuell risk för sina barn men kostinformation var delvis upp till dem själva att ta reda på. De VIII uttryckte känslor av osäkerhet och skuld om de råkat äta något ”förbjudet”. Rekommendationerna följdes så väl som möjligt, tillsammans med sunt förnuft för att hantera kostförändringar. Huvudteman var ”Söka information på egen hand”, ”Få professionell rådgivning när problem uppstår”, ”Känna sig osäker” och ”Ta ansvar med en nypa salt”. I studie II kunde man se vissa skillnader i kostmönster bland de gravida kvinnorna jämfört med kontrollgruppen: mindre intag av grönsaker (47 g/dag), potatis/ris/pasta (31 g/dag), kött/fisk (24 g/dag) och alkohol och tobak/snus och ett högre intag av kosttillskott. Både gravida kvinnor och kontrollgruppen hade lägre intag av folsyra via kosten med 45 % (gravida) och 22 % (kontrollgruppen) än de gällande rekommendationer som är (500 resp 400 g/dag). I studie III såg man att inta et av vitamin D var 34 % lägre än rekommendationen på 10 µg/dag. Minst en tredjedel av deltagarna hade otillräckliga plasma nivåer av vitamin D, under 50 nmol/L. Årstid var en stark faktor som påverkar det longitudinella mönstret. Graviditetsvecka, säsong, totala energiintaget, intaget av vitamin D och multivitamintillskott under de senaste 14 dagarna var faktorer som relaterade till Dvitaminnivåer. I studie IV sågs ett samband mellan allopregnanolon-koncentrationer vid graviditetsvecka 35 och viktökning från vecka 12 till 35 (p = 0,016). Det sågs också ett samband mellan ökningen av allopregnanolon (vecka 12–35) och viktökningen (se ovan) (p = 0,028).


Kostrekommendationer beskrevs som motsägelsefulla och förvirrande och kostråden de fick uppfattades som otillräckliga. Kvinnorna tog itu med sina kostförändringar och sökte information på egen hand men hade önskat mer omfattande råd från barnmorskan. Intaget av vitaminer viktiga för graviditeten var lägre än rekommendationerna, vilket också bekräftas av låga plasmanivåer av D-vitamin hos cirka en tredjedel av de gravida kvinnorna. D-vitaminnivåerna nådde en topp i slutet av graviditeten. Graviditetsvecka och säsong på året påverkade D vitaminnivåer, så även intag via mat och kosttillskott. Orsakertill viktökning är komplexa och beror på många faktorer. Allopregnanolon är en faktor som sågs relatera till viktökningen hos de undersökta gravida kvinnorna.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2016. 85 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1771
pregnancy, antenatal care, dietary advice, qualitative, dietary intake, cross-sectional, vitamin D levels, alloprenanolone, weight gain, longitudinal
National Category
Family Medicine Obstetrics, Gynecology and Reproductive Medicine
Research subject
Clinical Chemistry
urn:nbn:se:umu:diva-117427 (URN)978-91-7601-395-3 (ISBN)
Public defence
2016-04-08, Sal 135, byggnad 9A bottenvåningen, Norrlands universitetssjukhus, Umeå, 13:00 (Swedish)
Available from: 2016-03-09 Created: 2016-02-29 Last updated: 2016-03-07Bibliographically approved

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