Pregnancy · Rh Disease Prevention
Anti-D — Rhesus Negative Pregnancy
Why Rh-negative mums need anti-D injections at 28 weeks and after birth: prevents haemolytic disease in future pregnancies. Also after any sensitising event (bleeding, trauma, miscarriage, procedure). cffDNA screening from 11-13 weeks can identify when anti-D isn't needed. NICE NG201.
Last reviewed 2 June 2026
Anti-D immunoglobulin dosing
Routine antenatal + sensitising-event ladder
Region
Event / indication
Recommended dose
300 µg (1500 IU) IM at 28 wk
ACOG PB 181: single dose at 28 wk for all Rh-negative non-sensitised mothers. Some centres add second dose at 32 wk in extra-long pregnancies.
Troubleshooting + common pitfalls
- Pitfall: Giving anti-D to an already-sensitised mother.
Solution: Confirm anti-D antibody NEGATIVE on group + screen before prophylaxis. Sensitised women do not benefit (antibodies already formed) — they need MCA-PSV surveillance and possible IUT instead. - Pitfall: Skipping the post-delivery dose because the antenatal dose was given.
- Solution: Antenatal prophylaxis does NOT replace the post-delivery dose. Both are needed if the neonate is Rh-positive.
- Pitfall: Giving 300 µg without KB for a large APH at term.
Solution: ≥ 20 wk events ALWAYS need KB. A massive FMH (e.g. abruption) can exceed 30 mL and need 4–6 vials. Single standard dose may be inadequate. - Pitfall: Anti-D in known Rh-negative neonate.
Solution: Confirm cord blood Rh BEFORE the post-delivery dose. If neonate Rh-negative, anti-D is unnecessary and shouldn't be given. - Pitfall: > 72-hour window missed.
Solution: Give anti-D up to 10 days after the event — partial protection. Some studies show benefit even at 28 days. “Too late” is > 28 days, not > 72 hours. - Pitfall: Anti-D in spontaneous < 12 wk miscarriage (UK practice).
Solution: RCOG GTG 22: NOT routinely required in uncomplicated spontaneous miscarriage < 12 wk WITHOUT instrumentation. ACOG is more inclusive — check local policy. - Pitfall: Confusing weak D / Du-positive mother as needing anti-D.
Solution: Most weak D / partial D individuals don’t produce anti-D antibodies and may not need prophylaxis. RHD genotyping clarifies; haematology / transfusion medicine input. - Pitfall: Treating mother of known Rh-negative father as needing anti-D.
Solution: Genuinely Rh-negative father (confirmed homozygous) → fetus will be Rh-negative → no need for prophylaxis. Cell-free fetal DNA (cffDNA) for RHD typing is increasingly used (NICE DG25) and confirms fetal type non-invasively. - Pitfall: ECV without anti-D in Rh-negative mother.
Solution: ECV is a sensitising event — give anti-D within 72 h after the procedure regardless of success. - Pitfall: Routine antenatal dose given at 28 wk — then mother has APH at 30 wk — team thinks “already covered”.
Solution: Antenatal prophylaxis does NOT cover subsequent sensitising events. Give additional anti-D + KB for the new event. - Pitfall: Anti-D given IV instead of IM.
Solution: Most preparations are IM only (deltoid or anterolateral thigh). Some preparations are licensed IV for thrombocytopenia in ITP but not for HDFN prophylaxis. Check label. - Pitfall: Documentation gaps — missed dose detected at next pregnancy.
Solution: Always document anti-D dose, date, batch, and indication in maternal handheld notes. Antibody screen at each pregnancy booking catches missed prophylaxis.
Educational tool only — not medical advice. ACOG PB 181; RCOG GTG 22; NICE TA156; BCSH 2014. Anti-D administration is by midwives / obstetric / transfusion teams with antibody screen on file.
What does this mean?
Anti-D prophylaxis is one of the most consequential public-health interventions of 20th-century obstetrics — before its introduction, Rh-D alloimmunisation caused severe haemolytic disease of the fetus and newborn (HDFN) in many Rh-negative mothers and their second-and-subsequent Rh-positive babies. The standard regimen is: routine antenatal dose at 28 weeks (single or two-dose) for every Rh-negative non-sensitised mother; post-delivery dose within 72 hours if the neonate is Rh-positive (independent of the antenatal dose); additional dose for every sensitising event (procedure, trauma, bleed, ECV). The single most common error is giving anti-D to an already-sensitised woman — check the antibody screen first; if anti-D is present, prophylaxis doesn’t help and the focus shifts to MCA-PSV fetal-anaemia surveillance and possible intrauterine transfusion. Kleihauer-Betke testing is mandatory for any ≥ 20-week sensitising event because large fetomaternal haemorrhages exceed the standard dose’s 30 mL coverage. The newer non-invasive RHD genotyping by cell-free fetal DNA (NICE DG25) lets units skip antenatal prophylaxis in women whose fetus is confirmed Rh-negative — saving roughly one-third of doses.
What is anti-D and why do I need it?
Anti-D immunoglobulin is an injection given to Rh-NEGATIVE pregnant women to prevent serious complications in FUTURE pregnancies.
About 15% of women are Rh-negative. If baby is Rh-positive (likely if dad is positive), small amounts of baby’s blood can enter your bloodstream. Your immune system may make anti-D antibodies — these don’t affect THIS pregnancy but in future pregnancies attack baby’s blood cells (haemolytic disease of newborn).
Anti-D Ig prevents you making those antibodies.
How do I know if I need it?
- Booking blood tests: blood group + Rh + antibody screen.
- If Rh-negative: anti-D pathway begins.
- Checked again at 28 weeks.
- Some UK trusts: cffDNA at 11-13 weeks determines baby’s Rh.
When is anti-D given?
- Routine antenatal: at 28 weeks. UK: 1500 IU once OR 500 IU at 28 + 34 wk. US: 300 µg at 28 wk.
- Postnatal: within 72h if baby Rh-positive.
- Sensitising events: extra anti-D within 72h.
Sensitising events
Any event where baby’s blood might enter yours (after 12 weeks):
- Vaginal bleeding.
- Abdominal trauma (fall, car accident).
- Amniocentesis, CVS.
- ECV (turning breech baby).
- Miscarriage (after 12 wk).
- Ectopic pregnancy.
- Termination.
- Stillbirth.
- Antepartum haemorrhage.
- Any intrauterine procedure.
Under 12 weeks uncomplicated miscarriage WITHOUT instrumentation: anti-D not routinely needed.
Tell midwife of any event so anti-D given within 72h.
What if I don’t get anti-D when needed?
Sensitisation risk ~16% without anti-D vs <1% with. Once sensitised, can’t reverse.
Future pregnancies: anti-D antibodies cross placenta, attack baby’s red cells. Causes severe anaemia, jaundice, hydrops fetalis, possibly fetal death. Prevention is far preferable.
cffDNA / fetal Rh testing
Blood test from mum at 11-13 weeks. Detects baby’s RhD gene from placental DNA in mum’s blood.
- Baby Rh-negative: no anti-D needed.
- Baby Rh-positive: standard anti-D pathway.
- Accuracy >99% from 11-13 wk.
- Saves ~40% of women unnecessary injections.
- NHS rolling out; routine Netherlands, Denmark.
Is anti-D safe?
Yes. Extensively used since 1968.
Side effects:
- Mild injection site pain (most common).
- Mild fever.
- Rare severe allergic reaction (<1 in 10,000).
- No transmission of viruses (donated plasma pathogen-inactivated).
Safe in breastfeeding.
Partner’s blood type
If dad is confirmed Rh-NEGATIVE: baby cannot be Rh-positive — anti-D not needed. Save unnecessary injection.
Otherwise (dad Rh-positive or unknown): assume baby could be Rh-positive — anti-D given. cffDNA test alternative.
Different scenarios — anti-D
Scenario 1: First Rh-neg pregnancy, no events, 28 weeks
Routine anti-D 1500 IU (UK) or 300 µg (US). Postpartum dose if baby Rh-positive.
Scenario 2: Rh-neg + miscarriage at 14 weeks
Anti-D 1500 IU within 72h. Pregnancy after 12 wk counts as sensitising event.
Scenario 3: Rh-neg + abdominal trauma at 22 wk
Anti-D + Kleihauer-Betke to quantify bleed; extra anti-D if large feto-maternal haemorrhage.
Scenario 4: Rh-neg + dad confirmed Rh-neg
No anti-D needed. Discuss confirmation testing for peace of mind.
Scenario 5: Second pregnancy with previous anti-D, no antibodies
Same pathway again: 28 wk dose + post-delivery if baby Rh-pos.
Care guidance — anti-D
- Booking blood tests establish Rh status.
- Consider cffDNA at 11-13 wk if available.
- Routine 28 wk dose (or 28 + 34 wk).
- Postnatal dose within 72h if baby Rh-pos.
- Tell midwife of any bleeding, trauma, or procedure.
- Within 72h of sensitising event.
- Kleihauer test if ≥20 wk event.
- Safe in breastfeeding.
- Future pregnancies: same pathway.
- Confirm dad’s blood type if unknown.
Sources
- NICE NG201. Antenatal care.
- RCOG Green-top Guideline 22. The use of anti-D immunoglobulin for rhesus D prophylaxis.
- NICE DG25. High-throughput non-invasive prenatal testing for fetal RHD genotype.
- BCSH. Guidelines for the use of prophylactic anti-D immunoglobulin.
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Frequently asked questions
What is anti-D and why do I need it?
ANTI-D IMMUNOGLOBULIN — injection given to Rh-NEGATIVE pregnant women to PREVENT a serious complication in future pregnancies. BACKGROUND: about 15% of women are RH-NEGATIVE (your blood type ends in '-' e.g. O-, A-, B-, AB-). IF baby is RH-POSITIVE (likely if dad is positive), small amounts of baby's blood can enter your bloodstream during pregnancy or birth. YOUR IMMUNE SYSTEM might respond by making ANTI-D antibodies — these don't affect THIS pregnancy but in FUTURE pregnancies can cross placenta and attack baby's blood cells (haemolytic disease of newborn — HDFN). ANTI-D IG prevents you making these antibodies.
How do I know if I need anti-D?
BOOKING BLOOD TESTS: blood group + Rh status + ANTIBODY screen. If you're Rh-NEGATIVE: ANTI-D pathway begins. CHECKED AGAIN at 28 weeks. SOME UK trusts (since 2021): Free fetal DNA (cffDNA) blood test at 11-13 weeks — can determine baby's Rh status from your blood; if baby Rh-NEGATIVE, no anti-D needed. SAVES unnecessary injections. NOT universal NHS yet. RH-POSITIVE women: no anti-D needed. ALWAYS check baby's blood after delivery — confirms if anti-D was needed.
When is anti-D given?
ROUTINE ANTENATAL: at 28 WEEKS for all Rh-NEGATIVE women (without anti-D antibodies). UK: single 1500 IU at 28 wk OR two 500 IU doses at 28 + 34 wk. US: single 300 µg at 28 wk. POSTNATAL: within 72 HOURS if baby Rh-POSITIVE (heel-prick blood test on baby confirms). SENSITISING EVENTS: extra anti-D within 72 hours of any potentially sensitising event (see below). EVENT-BASED dose may vary.
What's a 'sensitising event'?
ANY EVENT where baby's blood might enter your bloodstream. EXAMPLES (≥12 weeks): (1) Vaginal bleeding; (2) Abdominal trauma (falls, car accident); (3) AMNIOCENTESIS; (4) CVS (chorionic villus sampling); (5) ECV (external cephalic version — turning breech baby); (6) MISCARRIAGE (after 12 weeks); (7) ECTOPIC pregnancy; (8) TERMINATION; (9) STILLBIRTH; (10) ANTEPARTUM HAEMORRHAGE; (11) Intrauterine procedures. UNDER 12 WEEKS uncomplicated miscarriage WITHOUT instrumentation: anti-D NOT routinely needed (rates of sensitisation very low). TELL midwife of any event so anti-D can be given within 72 hours.
What if I don't get anti-D when I need it?
RISK OF SENSITISATION rises: ~16% without anti-D vs <1% with. ONCE SENSITISED (made antibodies), can't reverse. FUTURE PREGNANCIES: anti-D antibodies cross placenta, attack baby's red blood cells if baby Rh-positive. CAUSES: severe anaemia, jaundice at birth, in utero death (hydrops fetalis), brain damage, learning difficulties from severe jaundice (kernicterus). MODERN TREATMENT: intrauterine blood transfusion can save fetal life. PREVENTION FAR PREFERABLE to treating sensitised pregnancy. NEVER skip dose when offered.
Is anti-D safe?
YES. EXTENSIVELY USED since 1968. SIDE EFFECTS: (1) MILD: pain/swelling at injection site (most common); fever; mild allergic reaction. (2) RARE: severe allergic reaction (anaphylaxis) — <1 in 10,000. (3) NO TRANSMISSION of viruses — donated blood plasma is pathogen-inactivated. NO HARM to current pregnancy or fertility. SAFE in breastfeeding. PRODUCT name: Rhophylac, RhoGAM, WinRho, others (varies by country).
Will I need anti-D in next pregnancy?
YES — if you're Rh-negative AND remain unsensitised, anti-D continues to be given in every pregnancy where baby may be Rh-positive. SAME PATHWAY: booking + antibody screen; 28 weeks; sensitising events; postpartum if baby Rh-positive. IF SENSITISED (anti-D antibodies present): no further anti-D needed (too late to prevent); pregnancy managed differently — monitoring for fetal anaemia (MCA Doppler), possible intrauterine transfusion, neonatology team awareness.
What about anti-D and IVF / surrogacy?
RH-NEGATIVE women: same anti-D pathway in IVF pregnancy. SURROGACY: anti-D needed by GESTATIONAL CARRIER if she's Rh-negative — same pathway. EGG/SPERM DONATION: anti-D pathway depends on GESTATIONAL CARRIER'S blood type, not donors'. CONFUSING in some cases — confirm with specialist team. SAFE in all assisted reproduction scenarios.
Can my partner's blood type help?
IF DAD KNOWN to be RH-NEGATIVE: baby CANNOT be Rh-positive (Rh inheritance) — anti-D NOT needed. SAVES unnecessary injections. CONFIRM dad's blood type via lab test. IF DAD'S blood type uncertain / unknown / Rh-positive: assume baby could be Rh-positive — anti-D given. RECENTLY: cffDNA test (free fetal DNA, from mum's blood at 11-13 wk) detects baby's Rh status — avoids need to know dad's type. NICE NG201 supports cffDNA screening when available.
What's cffDNA / fetal Rh testing?
FREE FETAL DNA TEST — blood test from mum at 11-13 weeks. Detects RhD gene FROM BABY (placental DNA in mum's blood). IF baby Rh-NEGATIVE: no anti-D needed for this pregnancy. IF baby Rh-POSITIVE: standard anti-D pathway. ACCURACY: >99% reliable from 11-13 weeks. AVAILABLE in some UK trusts; routine in Netherlands, Denmark. NHS England rolling out — varies by region. SAVES ~40% of women unnecessary anti-D injections. NICE NG201 supports universal cffDNA screening when feasible.
Will I have an immune reaction to anti-D?
RARE — <1 in 10,000 for severe reaction. MILD SIDE EFFECTS COMMON: injection site soreness; mild fever; rash. SEVERE (anaphylaxis): facial swelling, breathing difficulty, hypotension — emergency. ALLERGY HISTORY: tell midwife (anti-D contains tiny amounts of blood products); skin test if very concerned. PRE-MEDICATION (antihistamine) for those with severe allergy history. NEVER skip anti-D without alternative plan — consequences serious.
What if I have a religious objection to blood products?
ANTI-D is a blood product (immunoglobulin from donated plasma). JEHOVAH'S WITNESS / other religious groups: discuss with consultant; some accept anti-D as 'minor fraction' of blood; others decline. ALTERNATIVES (limited): synthetic monoclonal anti-D in development; CURRENT alternatives all blood-derived. INFORMED CONSENT — if declining, understand risks for future pregnancies. WRITTEN DOCUMENTATION. Discuss alternatives like fetal Rh screening to confirm anti-D needed at all.
What does Kleihauer-Betke test do?
BLOOD TEST that COUNTS fetal red cells in mum's blood. USED for: (1) Quantifying after sensitising event ≥20 wk — determines if standard anti-D dose is enough or more is needed; (2) After delivery if higher concern about feto-maternal haemorrhage; (3) After abdominal trauma. RESULT: percentage of fetal cells × maternal blood volume = estimated bleed volume. EXTRA anti-D given if large bleed. DOESN'T REPLACE routine anti-D — adjuncts the dose.
What if I'm Rh-positive — do I need anything?
NO anti-D needed (you can't make anti-D antibodies). YOUR BABY (whose blood type doesn't matter to you in pregnancy): can be any type without affecting your immune system. STANDARD antenatal care continues. RARE EXCEPTIONS: other red cell antibodies (anti-Kell, anti-Duffy, etc.) — different pathway. ROUTINE antibody screen at booking detects most. RHESUS-POSITIVE women: no anti-D pathway involvement at all.
Can I still breastfeed after anti-D?
YES — completely fine. ANTI-D is safe in breastfeeding. NO impact on milk supply or baby's health. INJECT at routine time; nurse / express / continue normal feeding. NO TIMING restrictions around feeds. SOME MUMS find slight injection site soreness — paracetamol fine for relief, fully compatible with breastfeeding.
How does this relate to other calculators on BumpBites?
Companion: /calculators/blood-type for understanding Rh status; /calculators/kleihauer-betke for quantification after events; /calculators/newborn-bilirubin (jaundice can be from haemolytic disease); /calculators/recurrent-miscarriage; /calculators/methotrexate-ectopic (anti-D sometimes given); /calculators/pregnancy-week for timing.