Dietary fat intake and gestational weight gain in relation to estradiol and progesterone plasma levels during pregnancy: a longitudinal study in Swedish women

Marie Lof,Wei Yu,Leena Hilakivi-Clarke,Elisabete Weiderpass,Sven Sandin S,Sonia de Assis

doi:10.1186/1472-6874-9-10

Abstract

BackgroundElevated pregnancy hormone levels, such as oestrogen and progesterone, may increase the risk of developing breast cancer both in mothers and offspring. However, the reasons for large inter-individual variations in estrogen and progesterone levels during pregnancy remain unknown. The objectives of this study were to investigate whether a) intakes of total dietary fat, types of fat (monounsaturated: MUFA, polyunsaturated: n-3 and n-6 PUFA, and saturated) and b) gestational weight gain are associated with estradiol and progesterone levels in plasma during pregnancy.MethodsWe measured body weight as well as estradiol and progesterone in plasma among 226 healthy pregnant Swedish women on gestation weeks 12, 25 and 33. At the same time points, dietary intake of total fat and types of fat (MUFA, PUFA, SFA, n-3 and n-6 PUFA) were estimated using 3-day food diaries.ResultsA large variation in estradiol and progesterone levels was evident.Nulliparous women had 37%, 12% and 30% higher mean estradiol levels on gestation weeks 12, 25 and 33 compared to parous women (P = 0.008). No associations were found between dietary intake of total fat or fat subtypes (including n-3 PUFA and n-6 PUFA) and plasma estradiol or progesterone levels. Gestational weight gain was associated with progesterone levels (P = 0.03) but the effect was very small (20% increase in progesterone levels between gestational weeks 12 and 33 per kg body weight/week).ConclusionNo associations among gestational weight gain, maternal dietary fat intake (total or subtypes including n-3 PUFA and n-6 PUFA) and plasma estradiol levels were found. However, pregnancy progesterone levels correlated with weight gain during pregnancy. Identification of other possible determinants of pregnancy estradiol and progesterone levels, important for the development of breast cancer in both mothers and offspring, are needed.

Highlights

Elevated pregnancy hormone levels, such as oestrogen and progesterone, may increase the risk of developing breast cancer both in mothers and offspring
We present here results from a prospective cohort study in pregnant Swedish women whose intakes of a) total dietary fat, types of fat and b) gestational weight gain were compared to plasma estradiol and progesterone levels on gestation weeks 12, 25 and 33
The mean estradiol levels were 600% higher on gestation week 25 compared to gestation week 12 (P < 0.0001) and 150% higher on gestational week 33 compared to gestational week 25 (P < 0.0001)

Summary

Introduction

Elevated pregnancy hormone levels, such as oestrogen and progesterone, may increase the risk of developing breast cancer both in mothers and offspring. A large body of epidemiological evidence shows that a high birth weight increases breast cancer risk [2,3]. The biological mechanisms underlying these associations are not fully known, but variations in maternal hormone levels during pregnancy e.g. estrogens or progesterone have been proposed to play a role [1,4]. The estrogenhypothesis is supported by findings showing that pregnant women [5] who haven taken diethylstilbestrol (a synthetic estrogen) exhibit increased breast cancer risk, and the findings from a nested-case control study in which women with higher pregnancy estrone levels during the third trimester had a two-fold incidence of breast cancer compared to controls [6]. Hispanic women who are at lower risk of breast cancer than Caucasian women have been reported to have the lowest pregnancy levels of progesterone [9]

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