Department of Epidemiology, Boston University School of Public Health, Boston, MA, USA.
Departments of Urology and Obstetrics and Gynecology, Stanford University School of Medicine, Stanford, CA, USA.
Hum Reprod. 2023 Aug 1;38(8):1601-1612. doi: 10.1093/humrep/dead100.
To what extent is male fatty acid intake associated with fecundability among couples planning pregnancy?
We observed weak positive associations of male dietary intakes of total and saturated fatty acids with fecundability; no other fatty acid subtypes were appreciably associated with fecundability.
Male fatty acid intake has been associated with semen quality in previous studies. However, little is known about the extent to which male fatty acid intake is associated with fecundability among couples attempting spontaneous conception.
STUDY DESIGN, SIZE, DURATION: We conducted an internet-based preconception prospective cohort study of 697 couples who enrolled during 2015-2022. During 12 cycles of observation, 53 couples (7.6%) were lost to follow-up.
PARTICIPANTS/MATERIALS, SETTING, METHODS: Participants were residents of the USA or Canada, aged 21-45 years, and not using fertility treatment at enrollment. At baseline, male participants completed a food frequency questionnaire from which we estimated intakes of total fat and fatty acid subtypes. We ascertained time to pregnancy using questionnaires completed every 8 weeks by female participants until conception or up to 12 months. We used proportional probabilities regression models to estimate fecundability ratios (FRs) and 95% CIs for the associations of fat intakes with fecundability, adjusting for male and female partner characteristics. We used the multivariate nutrient density method to account for energy intake, allowing for interpretation of results as fat intake replacing carbohydrate intake. We conducted several sensitivity analyses to assess the potential for confounding, selection bias, and reverse causation.
Among 697 couples, we observed 465 pregnancies during 2970 menstrual cycles of follow-up. The cumulative incidence of pregnancy during 12 cycles of follow-up after accounting for censoring was 76%. Intakes of total and saturated fatty acids were weakly, positively associated with fecundability. Fully adjusted FRs for quartiles of total fat intake were 1.32 (95% CI 1.01-1.71), 1.16 (95% CI 0.88-1.51), and 1.43 (95% CI 1.09-1.88) for the second, third, and fourth vs the first quartile, respectively. Fully adjusted FRs for saturated fatty acid intake were 1.21 (95% CI 0.94-1.55), 1.16 (95% CI 0.89-1.51), and 1.23 (95% CI 0.94-1.62) for the second, third, and fourth vs the first quartile, respectively. Intakes of monounsaturated, polyunsaturated, trans-, omega-3, and omega-6 fatty acids were not strongly associated with fecundability. Results were similar after adjustment for the female partner's intakes of trans- and omega-3 fats.
LIMITATIONS, REASONS FOR CAUTION: Dietary intakes estimated from the food frequency questionnaire may be subject to non-differential misclassification, which is expected to bias results toward the null in the extreme categories when exposures are modeled as quartiles. There may be residual confounding by unmeasured dietary, lifestyle, or environmental factors. Sample size was limited, especially in subgroup analyses.
Our results do not support a strong causal effect of male fatty acid intakes on fecundability among couples attempting to conceive spontaneously. The weak positive associations we observed between male dietary fat intakes and fecundability may reflect a combination of causal associations, measurement error, chance, and residual confounding.
STUDY FUNDING/COMPETING INTEREST(S): The study was funded by the National Institutes of Health, grant numbers R01HD086742 and R01HD105863. In the last 3 years, PRESTO has received in-kind donations from Swiss Precision Diagnostics (home pregnancy tests) and Kindara.com (fertility app). L.A.W. is a consultant for AbbVie, Inc. M.L.E. is an advisor to Sandstone, Ro, Underdog, Dadi, Hannah, Doveras, and VSeat. The other authors have no competing interests to report.
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男性脂肪酸摄入量与计划妊娠的夫妇的生育能力有多大关联？
我们观察到男性膳食中总脂肪和饱和脂肪酸的摄入量与生育能力呈弱正相关；其他脂肪酸亚类与生育能力没有明显关联。
先前的研究表明，男性脂肪酸摄入与精液质量有关。然而，关于男性脂肪酸摄入与试图自然受孕的夫妇生育能力的关联程度，知之甚少。
研究设计、规模、持续时间：我们进行了一项基于互联网的前瞻性孕前队列研究，共有 697 对夫妇参与，招募时间为 2015 年至 2022 年。在 12 个观察周期中，有 53 对夫妇（7.6%）失访。
参与者/材料、地点、方法：参与者为美国或加拿大的居民，年龄在 21-45 岁之间，入组时未使用生育治疗。在基线时，男性参与者完成了一份食物频率问卷，我们从中估计了总脂肪和脂肪酸亚类的摄入量。通过女性参与者每 8 周完成的问卷来确定妊娠时间，直到怀孕或达到 12 个月。我们使用比例概率回归模型来估计脂肪摄入量与生育能力的关联的生育能力比值（FRs）和 95%置信区间，同时调整了男性和女性伴侣的特征。我们使用多元营养密度方法来考虑能量摄入，以便解释结果为脂肪摄入替代碳水化合物摄入。我们进行了几项敏感性分析，以评估潜在的混杂、选择偏差和反向因果关系。
在 697 对夫妇中，我们在 2970 个月经周期的随访中观察到 465 次妊娠。考虑到删失后，12 个周期随访期间的累积妊娠率为 76%。总脂肪和饱和脂肪酸的摄入量与生育能力呈弱正相关。总脂肪摄入量四分位间距的完全调整 FR 分别为第二、第三和第四四分位间距与第一四分位间距相比为 1.32（95%CI 1.01-1.71）、1.16（95%CI 0.88-1.51）和 1.43（95%CI 1.09-1.88）。饱和脂肪酸摄入量的完全调整 FR 分别为第二、第三和第四四分位间距与第一四分位间距相比为 1.21（95%CI 0.94-1.55）、1.16（95%CI 0.89-1.51）和 1.23（95%CI 0.94-1.62）。单不饱和、多不饱和、反式、ω-3 和 ω-6 脂肪酸的摄入量与生育能力没有明显关联。在调整女性伴侣摄入的反式和 ω-3 脂肪后，结果相似。
局限性、谨慎的原因：食物频率问卷估计的膳食摄入量可能存在非差异错误分类，当暴露作为四分位数建模时，这种错误分类预计会使极端类别中的结果偏向于零。可能存在未测量的饮食、生活方式或环境因素的残余混杂。样本量有限，特别是在亚组分析中。
我们的结果不支持男性脂肪酸摄入量与试图自然受孕的夫妇生育能力之间存在强烈的因果关系。我们观察到男性膳食脂肪摄入量与生育能力之间的弱正相关可能反映了因果关系、测量误差、机会和残余混杂的综合作用。
研究资金/利益冲突：该研究由美国国立卫生研究院资助，资助编号为 R01HD086742 和 R01HD105863。在过去 3 年中，Presto 收到了 Swiss Precision Diagnostics（家用妊娠试验）和 Kindara.com（生育应用程序）的实物捐赠。L.A.W. 是 AbbVie，Inc. 的顾问。M.L.E. 是 Sandstone，Ro，Underdog，Dadi，Hannah，Doveras 和 VSeat 的顾问。其他作者没有利益冲突需要申报。
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