Place · Level 3
Pregnancy & Lactation Nutrition · The why behind it
叶酸要在怀孕前就开始 · 碘和胆碱也建大脑 · 吃两人份是误区 · DHA 减早产不是提智商 · 一切跟着你的产科医生
Last updated
Story path
- 1Folate · a door that shuts earlyFolate · a door that shuts early
- 2By stage · what to emphasize whenBy stage · what to emphasize when
- 3Two more brain-building nutrientsTwo more brain-building nutrients
- 4Iron · making more bloodIron · making more blood
- 5Where marketing outruns evidenceWhere marketing outruns evidence
- 6'Eating for two' + what to avoid'Eating for two' + what to avoid
- 7Lactation + the galactagogue truthLactation + the galactagogue truth
Chapter 1
Folate · a door that shuts early
Folate · a door that shuts early
The first thing to say about pregnancy nutrition is folate. The reason hides in the calendar: the fetal neural tube (the future brain and spinal cord) closes at about 24-28 days after conception — when many people don't yet know they're pregnant and haven't even missed a period.
So taking folate is something to start before pregnancy, not 'mention at the first prenatal visit'. Mechanistically, folate supplies the methyl groups the fast-dividing neural-tube cells need to build DNA. The general-population recommendation is 400-800 micrograms a day (USPSTF Grade A).
About that often-quoted 72%: it comes from the landmark 1991 MRC RCT and refers to high-risk women who already had a baby with a neural tube defect, using a high 4 mg/day dose, where recurrence risk fell 72% (RR 0.28). Don't attach that number to the everyday 400 micrograms — the population and the dose are different.
While we're here, one marketing claim to dismantle: that 'an MTHFR gene variant means you must take active folate (L-methylfolate)'. Guidelines (ACMG) don't recommend routinely testing that gene; ordinary folic acid works regardless of genotype, and 'active folate is better' is a sales pitch, not an evidence-based recommendation.
So taking folate is something to start before pregnancy, not 'mention at the first prenatal visit'. Mechanistically, folate supplies the methyl groups the fast-dividing neural-tube cells need to build DNA. The general-population recommendation is 400-800 micrograms a day (USPSTF Grade A).
About that often-quoted 72%: it comes from the landmark 1991 MRC RCT and refers to high-risk women who already had a baby with a neural tube defect, using a high 4 mg/day dose, where recurrence risk fell 72% (RR 0.28). Don't attach that number to the everyday 400 micrograms — the population and the dose are different.
While we're here, one marketing claim to dismantle: that 'an MTHFR gene variant means you must take active folate (L-methylfolate)'. Guidelines (ACMG) don't recommend routinely testing that gene; ordinary folic acid works regardless of genotype, and 'active folate is better' is a sales pitch, not an evidence-based recommendation.
机制 · 神经管是怎么合上的, 以及那扇门为什么关得这么早
神经管闭合这四个字听起来抽象, 但它其实是一个能在脑子里看见的动作。胚胎最早期是平的。在它的背侧, 一条细胞带先增厚成一片神经板——将来的整个大脑和脊髓, 此刻还只是这片平板。接着神经板的两侧边缘向上隆起, 变成两道神经褶, 中间凹下去成一条沟。两道褶继续向中线靠拢, 顶端碰到一起、粘合, 像拉链一样封起来: 先从中段合上, 再同时朝头端和尾端两个方向拉过去。封完, 那条沟就成了一根埋在背里的管——管的头端膨大成大脑, 其余部分拉长成脊髓。
这个动作对材料的要求非常苛刻, 因为它是靠细胞不停分裂堆出来的。 褶要立起来、要靠拢、要长出足够的新细胞把缺口填满, 每一步都需要大量新细胞; 而每造一个新细胞, 都得先把整套 DNA 完整复制一遍。
叶酸卡的就是这一步。 造 DNA 要用四种碱基, 其中一种 (胸腺嘧啶) 拿不到现成的, 必须由细胞临时加工出来——办法是给另一种碱基接上一个甲基。这个甲基由谁送? 由叶酸带着的一碳单位送。叶酸不够, 甲基就供不上; 甲基供不上, 这种碱基就造不出来; 碱基造不出来, DNA 复制就卡住, 细胞分裂慢下来。
于是在这个对速度要求最高的窗口里, 材料跟不上进度: 两道褶没能及时长到一起, 拉链就留下一段没拉上的口子。 口子留在头端, 大脑那一段无法正常成形; 留在尾端, 就是脊柱裂——脊髓的一段没有被完整包进去。位置不同, 表现不同, 但根子是同一件事: 一个必须按时完成的合拢动作, 没能按时完成。
这也解释了这件事为什么如此讲时间。 那扇门不是慢慢关上的, 它是合拢完成就结束了: 管一旦封好, 后面再补多少叶酸, 也不会把已经成形的结构重新打开、再合一次。叶酸能起作用的全部时间, 都在合拢发生之前和之中——而那正好落在很多人还没意识到自己怀孕的那几周。指南把起点放在备孕而不是确诊怀孕, 依据就在这里 (USPSTF)。
顺带说清一件常被误会的事: 叶酸在这里的角色不是给大脑补营养, 而是造 DNA 的原料供应。这也是为什么它的效果集中在这个特定的结构、这个特定的时间窗, 而不是吃得越久越聪明——用途不一样, 期待也就不该一样。
误区 · MTHFR 与活性叶酸: 这个卖点是怎么搭起来的
有 MTHFR 突变就必须吃活性叶酸流传得特别广, 值得把它拆开看——因为它的每一块砖都是真的, 只是砌成的那面墙是歪的。第一块砖 (真的): 叶酸进了身体要经过几步加工才能干活。 你吃进去的那个形态不是终点。它要先被还原, 再一步步转成能真正上工的形式, 其中一步由一种叫 MTHFR 的酶完成——它负责把一个中间形态转成带甲基的那一种, 也就是营销词里说的活性叶酸。
第二块砖 (也是真的): 这个酶的基因确实有常见的变异型。 带某些变异型的人, 酶的工作效率比别人低一些。
歪掉的是第三步的推理: 效率低一些 ≠ 这条路走不通。 通路慢一点, 只要原料给足, 产物照样造得出来——这就是为什么普通叶酸在各种基因型的人身上都管用。真正决定神经管缺陷少不少的, 是有没有按时补够, 不是你吃的是哪一种形态。
所以专业学会的立场很直接: 遗传学会 (ACMG) 明确不推荐把 MTHFR 基因检测当常规项目做——因为检测结果不会改变任何人的处理方式。一个不改变处理方式的检测, 唯一确定的产出是焦虑和账单。
那它为什么还是这么好卖? 因为它把一个人人适用的、便宜的、有几十年硬证据的东西, 换成了一个看起来更懂你的贵版本。你有个特殊基因这句话天然让人觉得被看见了; 而普通叶酸对你也一样管用听起来像是被敷衍。判断力恰恰体现在这里: 一个说法让你觉得更特别, 不等于它让你更安全。
回到真正要紧的那条链上——上一页那个合拢动作, 需要的是按时到场的原料。形态之争, 在有没有按时到场面前是个小问题。
Chapter 2
By stage · what to emphasize when
By stage · what to emphasize when
Rather than memorize a long supplement list, remember the rhythm — the body works on different things at different stages, and the emphasis shifts with them.
Preconception: folate 400-800 micrograms a day, started before a positive test (the neural-tube window closes early).
First trimester (organ formation): the neural tube closes and the brain gets going — folate, iodine, and choline matter most (the most sensitive stretch of the first 1,000 days; Cusick & Georgieff). This is also when morning sickness is worst and eating is hardest: small, frequent amounts, whatever you can keep down.
Second trimester (rapid growth): plasma expands, so iron need rises from 18 to 27 mg a day; the skeleton mineralizes fast, so calcium and vitamin D come up (about 300-350 mg of calcium is laid into fetal bone daily in late pregnancy; Kovacs 2016); DHA starts to matter.
Third trimester (the sprint): the brain's growth spurt plus the fetus actively stockpiling iron — iron and DHA peak; most of the baby's weight is gained in these three months.
One myth to correct along the way: energy does not double — roughly +0 kcal in the first trimester, ~+340 in the second, ~+450 in the third (IOM 2005) — about a snack or two.
In a line: folate, iodine, choline up front (organ formation); iron, calcium, DHA later (growing, building bone, the brain sprint).
Preconception: folate 400-800 micrograms a day, started before a positive test (the neural-tube window closes early).
First trimester (organ formation): the neural tube closes and the brain gets going — folate, iodine, and choline matter most (the most sensitive stretch of the first 1,000 days; Cusick & Georgieff). This is also when morning sickness is worst and eating is hardest: small, frequent amounts, whatever you can keep down.
Second trimester (rapid growth): plasma expands, so iron need rises from 18 to 27 mg a day; the skeleton mineralizes fast, so calcium and vitamin D come up (about 300-350 mg of calcium is laid into fetal bone daily in late pregnancy; Kovacs 2016); DHA starts to matter.
Third trimester (the sprint): the brain's growth spurt plus the fetus actively stockpiling iron — iron and DHA peak; most of the baby's weight is gained in these three months.
One myth to correct along the way: energy does not double — roughly +0 kcal in the first trimester, ~+340 in the second, ~+450 in the third (IOM 2005) — about a snack or two.
In a line: folate, iodine, choline up front (organ formation); iron, calcium, DHA later (growing, building bone, the brain sprint).
数字 · 多出来的那点能量去哪了 (以及为什么不是翻倍)
顺带纠一个误区: 能量并不用翻倍——孕早期约多 0 大卡、孕中期约多 340、孕晚期约多 450 (IOM 2005), 大概就是一两份加餐。为什么这么少? 因为长一个人出来这件事没有想象中贵, 而且它是分阶段贵起来的。
孕早期几乎不用加, 这一条最反直觉。原因是这个阶段的工作量不在体积上, 而在排布上: 胚胎小到用克来称, 但它正在决定哪一片细胞变成心脏、哪一片合成神经管、哪一片长成肾。这是一场图纸阶段的工作, 消耗的是精确的原料 (叶酸、碘、胆碱这一类), 不是大量的热量。所以这几周吃不下东西的时候, 该担心的往往不是热量够不够, 而是这些关键原料有没有到位。 偏偏孕吐最重的也正是这几周。
中晚期才真的开始花钱, 而钱主要花在三个地方: 一是胎儿自己在长; 二是胎盘——它不是一根管子, 而是一个全天运转的加工厂, 自己也在代谢; 三是母体这边的改造, 血容量扩大意味着心脏要一直搬运更多的血, 子宫和乳腺也在增厚。这三笔加起来, 才是那多出来的几百大卡。
吃两人份这个说法为什么特别顽固? 因为它听起来像是对辛苦的补偿, 而且没有人会因为多吃而被指责。但账其实很清楚: 多出来的这点能量, 大约就是一两份像样的加餐。真正需要翻倍的从来不是热量, 是每一口的质量——同样是一份加餐, 里面装的是什么, 决定了上面那些精确的原料够不够。
Chapter 3
Two more brain-building nutrients
Two more brain-building nutrients
Besides folate, two more nutrients help build the brain but are often overlooked.
Iodine is the raw material for thyroid hormone, and thyroid hormone directly governs fetal brain development. The WHO calls iodine deficiency 'the world's most prevalent, yet easily preventable, cause of brain damage'. The pregnancy requirement rises to about 250 micrograms a day (WHO), and the American Thyroid Association recommends an extra 150 microgram iodine supplement because many prenatal vitamins contain none.
Choline is the most under-appreciated one. Its adequate intake (AI) is 450 milligrams a day, yet about 90% of pregnant people fall short, and prenatal vitamins usually contain little if any. Choline matters for the fetal brain in animals and mechanistically; but to be honest, the human cognitive benefit so far rests on one very small RCT (about 26 people, on a surrogate outcome) — so the wording should be 'may help', not 'makes babies smarter'.
Iodine is the raw material for thyroid hormone, and thyroid hormone directly governs fetal brain development. The WHO calls iodine deficiency 'the world's most prevalent, yet easily preventable, cause of brain damage'. The pregnancy requirement rises to about 250 micrograms a day (WHO), and the American Thyroid Association recommends an extra 150 microgram iodine supplement because many prenatal vitamins contain none.
Choline is the most under-appreciated one. Its adequate intake (AI) is 450 milligrams a day, yet about 90% of pregnant people fall short, and prenatal vitamins usually contain little if any. Choline matters for the fetal brain in animals and mechanistically; but to be honest, the human cognitive benefit so far rests on one very small RCT (about 26 people, on a surrogate outcome) — so the wording should be 'may help', not 'makes babies smarter'.
机制 · 甲状腺激素和胆碱, 各自在大脑里做什么
上一屏说了碘管大脑发育, 却没说它是怎么管的。把这一步补上, 你就能理解为什么缺碘的后果赶不上、也补不回来。碘 → 甲状腺激素 → 大脑的布线工。 甲状腺激素这个分子本身就挂着碘原子——碘不是帮助造它, 碘是它的零件。零件不够, 产量就下来。
甲状腺激素进入正在发育的脑组织后, 管的是施工调度: 新生的神经元该往哪一层迁移、迁到哪里停下、什么时候开始伸出突起去连别的神经元; 还有一类叫少突胶质细胞的细胞, 在它的指挥下给神经纤维裹上髓鞘——那是一层绝缘的包裹, 有了它, 信号才跑得又快又准。
关键在于这些工序是有档期的。 神经元迁移和裹髓鞘各有自己的时段, 过了就进下一道工序。缺碘造成的不是长得慢一点, 而是布线阶段的错位; 而布线阶段不会重开。这就是世界卫生组织那句话的分量所在: 它说可预防, 是因为在窗口里把碘给足就不会发生; 它同时也意味着窗口之外再给, 已经不是同一件事。
还有一个容易被忽略的细节: 孕早期胎儿自己的甲状腺还没开工, 那段时间大脑用的甲状腺激素来自母亲, 穿过胎盘送过去。所以在最早、也最关键的那一段里, 母亲的碘状况是胎儿唯一的来源。
胆碱走的是另一条路, 而且一路分三支。 第一支, 它是磷脂酰胆碱的原料——细胞膜的主要成分之一。大脑在这段时间里每天都在造大量新细胞, 每个新细胞都要一整张新膜, 膜的材料就来自这里。第二支, 它是乙酰胆碱的原料——一种神经递质, 参与记忆相关的通路。第三支, 它是一个甲基供体, 和叶酸共用同一个一碳池: 一边紧张的时候, 另一边会被拉去顶班。
所以叶酸和胆碱不是两件各管各的事, 它们是同一个系统的两半。 这也解释了为什么只盯着叶酸并不足够——同一个甲基池要同时供应造 DNA 和造细胞膜, 一边被抽空, 另一边也会紧。
最后把分寸放回来: 胆碱这条链在机制和动物研究上很清楚, 但人身上的认知获益证据仍然很薄 (就是上一屏说的那项很小的试验)。所以正确的说法始终是可能有帮助, 而不是让宝宝更聪明——机制讲得通和在人身上被证明是两件事, 这一整篇都在练这个区分。
Chapter 4
Iron · making more blood
Iron · making more blood
In pregnancy, the plasma (the liquid part of blood) expands by about 40-50%, while red-cell numbers can't keep pace — so the blood is diluted and labs can look anemic (physiologic dilutional anemia); on top of that, the fetus and placenta genuinely need iron. So the iron recommendation rises from 18 to 27 milligrams a day.
Here's a real, worth-knowing guideline disagreement:
The American College of Obstetricians and Gynecologists (ACOG): screen every pregnant person with a blood count (first trimester + 24-28 weeks) for anemiaUSPSTF 2024: gave routine screening and supplementation in asymptomatic pregnant people an 'I' (insufficient evidence) rating
Read that 'I' correctly: it means the current evidence is insufficient to weigh benefit against harm — not 'don't screen'; and it explicitly excludes symptomatic and high-risk people. The two sides are a documented disagreement, not a right-and-wrong — what to actually do, follow your OB.
Here's a real, worth-knowing guideline disagreement:
The American College of Obstetricians and Gynecologists (ACOG): screen every pregnant person with a blood count (first trimester + 24-28 weeks) for anemiaUSPSTF 2024: gave routine screening and supplementation in asymptomatic pregnant people an 'I' (insufficient evidence) rating
Read that 'I' correctly: it means the current evidence is insufficient to weigh benefit against harm — not 'don't screen'; and it explicitly excludes symptomatic and high-risk people. The two sides are a documented disagreement, not a right-and-wrong — what to actually do, follow your OB.
Chapter 5
Where marketing outruns evidence
Where marketing outruns evidence
This screen is for building judgment: two nutrients sold hard, on evidence that's less miraculous than the pitch.
DHA (an omega-3): the genuinely solid benefit is reducing preterm birth (Cochrane: <37 weeks RR 0.89, <34 weeks RR 0.58), not raising IQ. The most-quoted 'DHA makes babies smarter' largely fell flat in big trials (DOMInO, followed to age 4, no cognitive difference). So the reason to take DHA in pregnancy is preterm protection, not 'a smarter baby'.
Vitamin D: the recommendation is 600 IU a day. After its 2024 update, Cochrane downgraded the claims about preventing pre-eclampsia, gestational diabetes, and improving birthweight to low or very-low certainty (the confidence intervals all cross the line of no effect). ACOG doesn't recommend routinely screening everyone's vitamin D — rather, supplement when there's documented deficiency (1,000-2,000 IU).
The takeaway: neither is 'more is better, everyone megadose' — it's about being clear on what to supplement, and for whom.
DHA (an omega-3): the genuinely solid benefit is reducing preterm birth (Cochrane: <37 weeks RR 0.89, <34 weeks RR 0.58), not raising IQ. The most-quoted 'DHA makes babies smarter' largely fell flat in big trials (DOMInO, followed to age 4, no cognitive difference). So the reason to take DHA in pregnancy is preterm protection, not 'a smarter baby'.
Vitamin D: the recommendation is 600 IU a day. After its 2024 update, Cochrane downgraded the claims about preventing pre-eclampsia, gestational diabetes, and improving birthweight to low or very-low certainty (the confidence intervals all cross the line of no effect). ACOG doesn't recommend routinely screening everyone's vitamin D — rather, supplement when there's documented deficiency (1,000-2,000 IU).
The takeaway: neither is 'more is better, everyone megadose' — it's about being clear on what to supplement, and for whom.
Chapter 6
'Eating for two' + what to avoid
'Eating for two' + what to avoid
'Eating for two' is a widespread myth. The extra energy is actually modest: about +0 kcal in the first trimester, ~+340 kcal in the second, ~+450 kcal in the third (IOM 2005) — roughly a snack or two, not double.
More important than 'eating more' is avoiding a few things, in order of certainty:
Alcohol: no known safe amount and no safe window (CDC / ACOG / US Surgeon General agree). This is the firmest — put it first.High-dose preformed vitamin A (retinol): above about 10,000 IU/day carries teratogenic risk (Rothman 1995, a prospective cohort). Note — beta-carotene is not teratogenic (the body converts it as needed), so carrots and squash are fine; the things to watch are animal liver and high-dose vitamin A supplements.High-mercury fish: avoid per the FDA/EPA 2021 list (shark, swordfish, king mackerel, Gulf of Mexico tilefish), and eat 8-12 oz/week of lower-mercury fish instead.Listeria-prone foods: unpasteurized cheeses, deli meats, raw items (pregnancy raises infection risk far above baseline).
This avoid list is worth remembering more than any 'what to supplement'.
More important than 'eating more' is avoiding a few things, in order of certainty:
Alcohol: no known safe amount and no safe window (CDC / ACOG / US Surgeon General agree). This is the firmest — put it first.High-dose preformed vitamin A (retinol): above about 10,000 IU/day carries teratogenic risk (Rothman 1995, a prospective cohort). Note — beta-carotene is not teratogenic (the body converts it as needed), so carrots and squash are fine; the things to watch are animal liver and high-dose vitamin A supplements.High-mercury fish: avoid per the FDA/EPA 2021 list (shark, swordfish, king mackerel, Gulf of Mexico tilefish), and eat 8-12 oz/week of lower-mercury fish instead.Listeria-prone foods: unpasteurized cheeses, deli meats, raw items (pregnancy raises infection risk far above baseline).
This avoid list is worth remembering more than any 'what to supplement'.
Chapter 7
Lactation + the galactagogue truth
Lactation + the galactagogue truth
After birth, lactation does need a bit more energy, but less than imagined: a net increase of about 330 kcal/day (the often-heard 500 kcal is the gross cost of making milk, of which about 170 kcal comes from fat stored during pregnancy — so the amount you actually eat more is 330).
Two common myths:
'Chugging water makes more milk' — no evidence. A Cochrane review found that drinking beyond thirst doesn't raise supply. Drink to thirst is enough.'Galactagogue supplements (fenugreek, fennel, milk thistle) work' — the evidence is low to very-low certainty (2020 Cochrane); the Academy of Breastfeeding Medicine (ABM) explicitly cannot recommend any specific galactagogue, and the apparent effect may just be placebo. The first-line fix for low supply is effective, frequent milk removal, not herbs. (Safety note: fenugreek is a legume, so people allergic to peanuts/chickpeas may cross-react; it can also cause GI upset and lower blood sugar.)
To close: this page is general education to understand the why, not medical advice. Perinatal nutrition is highly individual — medications, existing conditions, prior pregnancies, diet, and labs all matter — so decide together with your OB or midwife. For the avoid-list, remember the highest-certainty ones first: alcohol and high-dose vitamin A.
Two common myths:
'Chugging water makes more milk' — no evidence. A Cochrane review found that drinking beyond thirst doesn't raise supply. Drink to thirst is enough.'Galactagogue supplements (fenugreek, fennel, milk thistle) work' — the evidence is low to very-low certainty (2020 Cochrane); the Academy of Breastfeeding Medicine (ABM) explicitly cannot recommend any specific galactagogue, and the apparent effect may just be placebo. The first-line fix for low supply is effective, frequent milk removal, not herbs. (Safety note: fenugreek is a legume, so people allergic to peanuts/chickpeas may cross-react; it can also cause GI upset and lower blood sugar.)
To close: this page is general education to understand the why, not medical advice. Perinatal nutrition is highly individual — medications, existing conditions, prior pregnancies, diet, and labs all matter — so decide together with your OB or midwife. For the avoid-list, remember the highest-certainty ones first: alcohol and high-dose vitamin A.
References · 24
- MRC Vitamin Study Research Group. (1991). Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. The Lancet, 338(8760), 131-137. 10.1016/0140-6736(91)90133-A
- Czeizel, A. E., & Dudás, I. (1992). Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. The New England Journal of Medicine, 327(26), 1832–1835. 10.1056/NEJM199212243272602
- US Preventive Services Task Force. (2023). Folic acid supplementation to prevent neural tube defects: US Preventive Services Task Force reaffirmation recommendation statement. JAMA, 330(5), 454-459. Grade A: all persons planning or capable of pregnancy take a daily supplement with 400-800 mcg folic acid. 10.1001/jama.2023.12876
- Hickey, S. E., Curry, C. J., & Toriello, H. V. (2013). ACMG practice guideline: lack of evidence for MTHFR polymorphism testing. Genetics in Medicine, 15(2), 153-156. Routine MTHFR genotyping is not recommended; folic acid is effective regardless of MTHFR genotype. 10.1038/gim.2012.165
- National Institutes of Health, Office of Dietary Supplements. (2022). Folate — Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/Folate-HealthProfessional
- Cusick, S. E., & Georgieff, M. K. (2016). The role of nutrition in brain development: the golden opportunity of the first 1000 days. The Journal of Pediatrics, 175, 16-21. 10.1016/j.jpeds.2016.05.013
- NIH Office of Dietary Supplements. Iron fact sheet for health professionals. The iron RDA rises from 18 mg/day to 27 mg/day in pregnancy to cover plasma volume expansion and fetal/placental demand. ods.od.nih.gov/factsheets/Iron-HealthProfessional
- Kovacs, C. S. (2016). Maternal mineral and bone metabolism during pregnancy, lactation, and post-weaning recovery. Physiological Reviews, 96(2), 449-547. 10.1152/physrev.00027.2015
- Institute of Medicine. (2005). Dietary Reference Intakes for Energy. Estimated additional energy needs in pregnancy are about +0 kcal/day (first trimester), +340 kcal/day (second), and +452 kcal/day (third). 10.17226/10490
- World Health Organization. Micronutrients: iodine deficiency disorders. WHO describes iodine deficiency as the world's most prevalent, yet easily preventable, cause of brain damage; pregnancy requirement ~250 mcg/day (WHO). www.who.int/health-topics/micronutrients
- American Thyroid Association (Becker, D. V., et al., 2006). Iodine supplementation for pregnancy and lactation. Thyroid, 16(10), 949-951. Recommends a 150 mcg/day iodine supplement during pregnancy and lactation, since many prenatal vitamins lack iodine. pubmed.ncbi.nlm.nih.gov/17042677
- NIH Office of Dietary Supplements. Choline fact sheet for health professionals. Adequate Intake in pregnancy is 450 mg/day (550 mg lactation); most pregnant people fall short and prenatal vitamins typically contain little if any choline. ods.od.nih.gov/factsheets/Choline-HealthProfessional
- Caudill, M. A., et al. (2018). Maternal choline supplementation during the third trimester improves infant information processing speed. FASEB Journal, 32(4), 2172-2180. A small RCT (n approximately 26) found a benefit on an infant surrogate cognitive measure; human cognitive evidence remains limited. 10.1096/fj.201700692RR
- American College of Obstetricians and Gynecologists. (2021). Anemia in pregnancy (Practice Bulletin 233). Obstetrics & Gynecology, 138(2), e55-e64. ACOG recommends screening all pregnant patients for anemia with a complete blood count in the first trimester and at 24-28 weeks. 10.1097/AOG.0000000000004477
- US Preventive Services Task Force. (2024). Screening and supplementation for iron deficiency anemia during pregnancy. JAMA. An 'I' statement: current evidence is insufficient to weigh the benefits and harms of routine screening and supplementation in asymptomatic pregnant persons (excludes symptomatic/high-risk). 10.1001/jama.2024.15196
- Middleton, P., et al. (2018). Omega-3 fatty acid addition during pregnancy. Cochrane Database of Systematic Reviews, CD003402.pub3. Higher-certainty benefit is reduced preterm birth (<37 weeks RR 0.89; <34 weeks RR 0.58); effects on cognition were not demonstrated. 10.1002/14651858.CD003402.pub3
- Makrides, M., et al. (2014). Four-year follow-up of children born to women in a randomized trial of prenatal DHA supplementation (DOMInO). JAMA, 311(17), 1802-1804. Prenatal DHA did not improve child cognitive outcomes at 4 years. 10.1001/jama.2014.2194
- Palacios, C., et al. (2024). Vitamin D supplementation during pregnancy. Cochrane Database of Systematic Reviews, CD008873.pub5. After removing weak studies, evidence for preventing pre-eclampsia, gestational diabetes, and improving birthweight was downgraded to low or very-low certainty (confidence intervals cross no effect). 10.1002/14651858.CD008873.pub5
- Rothman, K. J., et al. (1995). Teratogenicity of high vitamin A intake. New England Journal of Medicine, 333(21), 1369-1373. In a prospective cohort, preformed vitamin A above about 10,000 IU/day from supplements was associated with cranial-neural-crest birth defects (RR 4.8); beta-carotene was not teratogenic. 10.1056/NEJM199511233332101
- US Centers for Disease Control and Prevention. Alcohol use during pregnancy. There is no known safe amount of alcohol and no safe time to drink during pregnancy; alcohol can cause fetal alcohol spectrum disorders. www.cdc.gov/alcohol-pregnancy/about
- US FDA & EPA. (2021). Advice about eating fish. Pregnant and breastfeeding people should avoid the highest-mercury fish (shark, swordfish, king mackerel, Gulf of Mexico tilefish) and eat 8-12 oz/week of lower-mercury fish. www.epa.gov/choose-fish-and-shellfish-wisely/epa-fda-advice-about-eating-fish-and-shellfish
- Institute of Medicine. (2005). Dietary Reference Intakes for Energy (lactation). The net additional dietary energy in lactation is about +330 kcal/day (gross milk-energy cost ~500 kcal/day minus ~170 kcal/day mobilized from pregnancy fat stores). 10.17226/10490
- Ndikom, C. M., et al. (2014). Extra fluids for breastfeeding mothers for increasing milk production. Cochrane Database of Systematic Reviews, CD008758.pub2. No evidence that drinking beyond thirst increases milk supply; drink to thirst. 10.1002/14651858.CD008758.pub2
- Foong, S. C., et al. (2020). Oral galactagogues for increasing breast-milk production in mothers of non-hospitalised term infants. Cochrane Database of Systematic Reviews, CD011505.pub2. Evidence for fenugreek and other galactagogues is low to very-low certainty; effective, frequent milk removal is first-line. 10.1002/14651858.CD011505.pub2