A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 24-year-old woman visits her physician to seek preconception advice. She is recently married and plans to have a child soon. Menses occur at regular 28-day intervals and last 5 days. She has sexual intercourse only with her husband and, at this time, they consistently use condoms for birth control. The patient consumes a well-balanced diet with moderate intake of meat and dairy products. She has no history of serious illness and takes no medications currently. She does not smoke or drink alcohol. The patient’s history reveals no birth defects or severe genetic abnormalities in the family. Physical examination shows no abnormalities. Pelvic examination indicates a normal vagina, cervix, uterus, and adnexa. To decrease the likelihood of fetal neural-tube defects in her future pregnancy, which of the following is the most appropriate recommendation for initiation of folic acid supplementation?
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A
As soon as possibleCorrect. Folate stores must be adequate at conception to prevent NTDs (closure at 3–4 weeks post-conception), so supplementation should start immediately during preconception planning.
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B
In the second half of pregnancyIncorrect. Starting in the second half of pregnancy is far too late — neural tube closes by week 4 post-conception.
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C
When off contraceptionIncorrect. Waiting until off contraception risks an unplanned conception with inadequate folate; starting now protects against an early or unrecognized pregnancy.
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D
No folic acid supplement is required as nutritional sources are adequateIncorrect. Dietary folate is generally insufficient to reach the protective threshold; supplementation is recommended for all reproductive-age women regardless of diet.
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E
Once a positive pregnancy test is documentedIncorrect. Starting folate only after a confirmed pregnancy misses the critical window of neural tube closure (3–4 weeks post-conception), which often occurs before pregnancy is recognized.
↑ Tap an answer to reveal the reasoning
Answer: A. Neural tube closure occurs at 3–4 weeks post-conception (5–6 weeks gestational age) — often before a woman even knows she is pregnant. To meaningfully reduce neural tube defect (NTD) risk, folate stores must already be replete at the moment of conception. The USPSTF and CDC therefore recommend that all women capable of becoming pregnant take 400–800 mcg of folic acid daily, beginning as soon as preconception planning starts, not after a positive pregnancy test.
In this patient, preconception counseling is the perfect opportunity: she should begin folic acid supplementation immediately, well before stopping condoms. Waiting until she stops contraception or until pregnancy is confirmed risks missing the critical window of neural tube closure.
Women at higher risk (prior NTD-affected pregnancy, diabetes, antiepileptic use) require higher doses (4 mg/day). Dietary intake alone, even of a balanced diet, is typically insufficient to achieve the protective serum folate level needed.
**Why each option:**
**A.** Correct. Folate stores must be adequate at conception to prevent NTDs (closure at 3–4 weeks post-conception), so supplementation should start immediately during preconception planning.
**B.** Starting in the second half of pregnancy is far too late — neural tube closes by week 4 post-conception.
**C.** Waiting until off contraception risks an unplanned conception with inadequate folate; starting now protects against an early or unrecognized pregnancy.
**D.** Dietary folate is generally insufficient to reach the protective threshold; supplementation is recommended for all reproductive-age women regardless of diet.