Vitamin D for Women
Women have identical vitamin D requirements to men in isolation, but pregnancy, lactation, and menopause create distinct windows where dosing changes and where deficiency has larger consequences.
Reproductive-age adult dosing
- 19–50 years: 600 IU/day RDA; Endocrine Society 1,500–2,000 IU/day for adults at risk of deficiency.
- Pregnancy: 600 IU/day RDA, but many obstetric societies recommend 1,000–2,000 IU/day; the VDAART trial used 4,400 IU/day safely.
- Lactation: 600 IU/day RDA for mother; higher maternal doses (6,400 IU/day) can transfer enough vitamin D via breastmilk to meet the infant's requirement without direct infant drops.
- Perimenopausal (~50): 800 IU/day plus adequate calcium.
- Postmenopausal: 800–2,000 IU/day; higher targets when combined with anti-osteoporosis therapy.
Bone health and osteoporosis
Women lose ~10% of bone mineral density in the first 5 years post-menopause because of oestrogen withdrawal. Vitamin D + calcium is the foundation on which bisphosphonates, denosumab, or raloxifene act. See osteoporosis.
PCOS and fertility
Polycystic ovary syndrome (PCOS) is associated with high rates of vitamin D deficiency and metabolic dysregulation. Supplementation improves insulin sensitivity, may improve ovulation frequency, and (in trials with fertility outcomes) supports better response to ovulation induction. See PCOS.
Pregnancy
Maternal deficiency is associated with pre-eclampsia, gestational diabetes, low birthweight, and childhood asthma/wheeze. Supplementation reduces some of these outcomes in intervention trials. All prenatal vitamins should contain 600 IU cholecalciferol; higher doses (up to 4,000 IU/day) are commonly used and considered safe. See pregnancy.
Menopause and vasomotor symptoms
Vitamin D does not reduce hot flashes or night sweats. Its role in menopause is about bone protection, muscle strength (reducing fall/fracture risk), and modest benefits for mood and immunity — not vasomotor symptom control.
Endometriosis and menstrual pain
Small trials suggest vitamin D supplementation may reduce dysmenorrhoea (period pain) and endometriosis pain, likely via anti-inflammatory effects. Reasonable low-cost adjunct — not a substitute for evidence-based endometriosis therapy.