Vitamin D Supplementation in Vitamin D-Deficient Pregnant Women (First Trimester)

What Constitutes Deficiency?

• Deficiency: < 50 nmol/L (< 20 ng/mL) - IOM threshold
• Insufficiency/optimal (Endocrine Society standard): 75-100 nmol/L (30-40 ng/mL)

Which Form to Use

Dosing Recommendations (Confirmed Deficiency)

• Standard therapeutic dose: 1,000-2,000 IU/day (ACOG recommendation)
• If 25(OH)D is severely low (e.g., < 25 nmol/L) or the patient has risk factors for malabsorption (obesity, bariatric surgery, dark skin, minimal sun exposure): consider 3,000-4,000 IU/day, which remains within the established safe upper limit for pregnancy (4,000 IU/day per most guidelines)

Frequency

• Daily oral dosing is preferred over intermittent high-dose (weekly/monthly) during pregnancy
• The 2024 Endocrine Society Clinical Practice Guideline specifically recommends daily administration rather than high-dose intermittent regimens (PMID: 38828931)

Duration

• Throughout the entire pregnancy - start from the first trimester and continue until delivery
• The 2024 Endocrine Society guideline recommends empiric vitamin D for all pregnant women (regardless of baseline 25(OH)D) because it reduces risk of preeclampsia, preterm birth, intrauterine mortality, and neonatal mortality
• Continue postpartum if breastfeeding, as breast milk is a poor source of vitamin D (infant would need separate supplementation)

Monitoring

• Recheck 25(OH)D at 4-6 weeks after starting treatment to confirm response and adjust dose if needed
• Aim for a 25(OH)D of at least 50 nmol/L (conservative/IOM target) or 75-100 nmol/L (Endocrine Society target)
• Toxicity (hypercalcemia) is rare below 10,000 IU/day, but doses above 4,000 IU/day are generally not recommended in pregnancy without specialist guidance
• Note: prenatal vitamins typically contain 400-600 IU of vitamin D - this does NOT replace a therapeutic dose when deficiency is confirmed

High-Risk Groups to Screen and Treat

• Minimal sun exposure (veiled, housebound, high latitude)
• Dark skin pigmentation
• Obesity (BMI > 30)
• Malabsorptive conditions (Crohn's, bariatric surgery, celiac)
• Chronic use of anticonvulsants or antiretrovirals

Summary Prescription

Cholecalciferol (Vitamin D3) 1,000-2,000 IU orally once daily, starting in the first trimester and continuing throughout pregnancy. For severe deficiency or high-risk patients, up to 4,000 IU/day is safe and may be used. Recheck 25(OH)D in 4-6 weeks to confirm adequacy.

• Creasy & Resnik's Maternal-Fetal Medicine, p. 266 (ACOG guidance, Endocrine Society dosing targets)
• Endocrine Society Clinical Practice Guideline 2024 - PMID 38828931 - recommends empiric vitamin D for all pregnant women; daily dosing preferred
• Yang et al. 2025 systematic review/meta-analysis - PMID 38950419 - maternal/neonatal benefits of supplementation confirmed

Vitamin B12 Supplementation in Deficient Pregnant Women (First Trimester)

What Constitutes Deficiency?

Which Form to Use

• Hydroxocobalamin (IM injection) - preferred for parenteral therapy; longer-acting, retained better in the body
• Cyanocobalamin (oral tablets) - used for dietary deficiency or oral supplementation; IM cyanocobalamin is considered less suitable (NHS guidance)

Treatment Decision: Oral vs. Parenteral

Since most B12 deficiency is due to impaired absorption (not diet), parenteral treatment is the default in clinical practice. Oral B12 at high doses works via passive diffusion and can be used if parenteral therapy is not feasible.

Dosing Regimens

A. Parenteral (Hydroxocobalamin IM) - First-line for malabsorption

• Loading: Hydroxocobalamin 1 mg IM 3 times per week for 2 weeks (6 doses total)
• Maintenance: 1 mg IM every 2-3 months throughout pregnancy (and long-term if malabsorptive cause)
• For dietary-only deficiency: maintenance can be reduced to 1 mg IM twice yearly after loading

• Seek urgent haematology/neurology input
• Loading: Hydroxocobalamin 1 mg IM on alternate days until no further improvement (usually 3 weeks)
• Maintenance: 1 mg IM every 2 months

B. Oral (Cyanocobalamin or Hydroxocobalamin) - For dietary deficiency

• 1,000 mcg (1 mg) orally once daily
• High-dose oral B12 works via passive absorption even when intrinsic factor is absent, but response must be confirmed
• Recheck serum B12 at 3-4 weeks to confirm adequate response

Duration

• Loading course: as above (2-3 weeks)
• Continue maintenance throughout the entire pregnancy and postpartum (especially if breastfeeding, to prevent infant deficiency)
• If the cause is permanent (pernicious anaemia, surgical gastric loss): lifelong maintenance after delivery
• Dietary deficiency: continue until diet is corrected and confirmed adequate

Monitoring

• Iron status (ferritin, serum iron): B12 treatment stimulates erythropoiesis and can unmask or worsen iron deficiency - diagnose and treat iron deficiency concurrently
• Replace B12 before iron to reduce risk of subacute combined degeneration of the spinal cord
• If pernicious anaemia is suspected: test for intrinsic factor antibodies and anti-parietal cell antibodies
• If coeliac disease suspected: tissue transglutaminase antibodies

High-Risk Groups to Screen

Why First Trimester Matters

• Neural tube closure (alongside folate) - deficiency raises NTD risk
• DNA synthesis and cell division during rapid embryogenesis
• Placental development
• Maternal haematopoiesis

Important Safety Note

Summary Prescription

Confirmed dietary B12 deficiency: Cyanocobalamin (or hydroxocobalamin) 1,000 mcg orally once daily from first trimester, continued throughout pregnancy. Recheck B12 at 3-4 weeks.

Confirmed malabsorptive B12 deficiency (no neurological features): Hydroxocobalamin 1 mg IM three times per week for 2 weeks, then 1 mg IM every 2-3 months throughout pregnancy.

With neurological features: Hydroxocobalamin 1 mg IM on alternate days until no further improvement, then 1 mg IM every 2 months. Seek specialist input urgently.

• Creasy & Resnik's Maternal-Fetal Medicine, p. 1641 - parenteral B12 prevents neurological progression; maternal deficiency leads to fetal/neonatal deficiency
• NHS SPS Vitamin B12 in Pregnancy guidance; NICE NG239; WNHS/KEMH Clinical Guideline (updated April 2025)
• Finkelstein et al. 2024, Cochrane Systematic Review - PMID 38189492 - B12 supplementation reduces maternal deficiency risk (RR 0.38)
• Nie et al. 2025 meta-analysis - PMID 40573151 - B12 deficiency and neural tube defect risk

O'Leary Ligation and Tsirulnikov (Triple) Ligation

1. O'Leary Ligation (O'Leary Stitch)

Background

Vessels Targeted

Surgical Technique

1. Exteriorise the uterus out of the abdominal cavity to allow clear posterior visualisation
2. Extend the bladder flap laterally to the level of the round ligament, and mobilise the vesico-uterine peritoneum inferiorly - this protects the ureter
3. Identify the ascending uterine artery running along the lateral wall of the uterus
4. Suture placement: Pass a large absorbable suture (e.g., 1-0 Vicryl/chromic catgut) through the myometrium medial to the uterine vessels, at a point approximately 2-3 cm below the lower edge of the uterine incision (or 2-3 cm below the hysterotomy, at the level of the lower uterine segment)
5. The needle is then passed through an avascular window in the broad ligament, lateral to the uterine vessels, and tied down - this compresses the artery against the uterus without actually dividing it
6. Repeat bilaterally

Mechanism

Efficacy

• Immediately effective in approximately 80% of cases of PPH
• Success rate reported at 89-100% in case series

Indications

• PPH at cesarean section (most common setting)
• PPH at laparotomy after vaginal delivery
• Prophylactically in cases of known high risk (e.g., placenta previa, large leiomyoma)

Complications

• Ureteral injury (rare if bladder flap is properly extended and ureter identified)
• Failure (in ~20% of cases - proceed to next step)

2. Tsirulnikov Triple Ligation

Background

Vessels Targeted - Three Pairs

Distinguishing it from AbdRabbo's Stepwise Devascularisation

Efficacy

• Combined success rate of O'Leary + Tsirulnikov: approximately 90%
• When combined with Cho's uterine compression sutures: even higher
• Independent risk factor for failure: placenta accreta (Blanc et al., 2012)

Stepwise Approach to Surgical PPH Control

Medical (oxytocin, ergometrine, carboprost, misoprostol)
        ↓ fails
Uterine tamponade (Bakri balloon, uterine packing)
        ↓ fails
Laparotomy: O'Leary bilateral uterine artery ligation
        ↓ fails (~20%)
Tsirulnikov triple ligation (complete devascularisation)
        ↓ fails (~10%)
Bilateral hypogastric (internal iliac) artery ligation
        ↓ fails / not feasible
Peripartum hysterectomy (definitive)

Key Comparison

• Creasy & Resnik's Maternal-Fetal Medicine, p. 948 - O'Leary ligation as first-line after laparotomy for PPH
• Schwartz's Principles of Surgery, 11th ed. - O'Leary stitches described as sutures through myometrium compressing vessels
• Morel et al. (2011), PMID 21474415 - Tsirulnikov triple ligation described; preferred over AbdRabbo's ovarian pedicle ligation
• Uterine-sparing procedures review, AJOG (2023), PMID 37729440 - comparative efficacy of all techniques; ~90% success with triple ligation