Canterbury DHB

Management of Mother (Carrier Women)

Pre-pregnancy

• Pre-pregnancy counselling should be offered to all potential carriers.
• Refer to Pre-implantation Genetic Diagnosis (PGD)
• Establish carrier status.
• Determine factor VIII/IX gene abnormality.
• Assay clotting factor (VIII/IX) level.

Discuss each case with regional haematologist:

On diagnosis of pregnancy

For all pregnancies, actively enquire about a family history of bleeding disorder. Specifically ask about haemophilia A (factor VIII deficiency) and haemophilia B (factor IX deficiency, Christmas disease).

Plan management with obstetrician and haematologist.

For carrier mothers

Management depends on parents’ attitude to haemophilia and termination of pregnancy, guided by genetic counselling, and whether the mother is informative on DNA testing:

• For parents wishing to terminate pregnancy if fetus has severe haemophilia and mother informative on DNA testing, either:
  • perform chorionic villus sampling at 11 to 12 weeks and proceed to gene testing on males, or
  • determine sex of fetus by intravaginal ultrasound at 14 to 16 weeks. If male, proceed to amniocentesis and gene testing.
• For parents who do not wish to terminate but would like to know whether the fetus is affected and mother informative on DNA testing, as above, but make sure the parents are aware of the risks of CVS.
• For parents who do not want termination and are not insistent about prior knowledge of haemophilia status of fetus or mother not informative on DNA testing, determine sex of infant by conventional ultrasound during second trimester and:
  • if female fetus, manage mother as detailed below but no additional intervention needed for newborn.
  • if male fetus, 50% risk of haemophilia, so proceed as if fetus affected until proven otherwise.

During pregnancy

• Assay maternal factor VIII/IX level at booking. If reduced, repeat at in the third trimester or before any invasive procedures.
• If factor VIII/IX level < 50%, increase level to ≥50% for procedures such as CVS, amniocentesis, or termination.
• Factor VIII deficiency: recombinant factor VIII for procedures other than termination. desmopressin is acceptable for terminations.
• Factor IX deficiency: high-purity factor IX concentrates (avoid prothrombinex - thrombogenic)
• Discuss delivery plan. Have appropriate treatment available at the time of delivery in line with proposed treatment plan.

At onset of labour

• Plan for a vaginal delivery unless contraindicated for obstetric reasons.
• Avoid:
  • scalp monitoring
  • vacuum delivery
  • vaginal delivery of breech
  • prolonged labour, especially second stage, with early recourse to caesarean section.
• Usually avoid forceps delivery. However, forceps delivery may be less traumatic than caesarean section if:
  • head deeply engaged in pelvis, and
  • rotation not required, and
  • expectation of easy procedure, and
  • performed by experienced staff.

Postpartum

• For haemophilia A carrier, monitor factor VIII level daily after birth if < 50% before pregnancy (acute phase protein and level falls post delivery) give desmopressin or recombinant factor VIII if levels < 50% for:
  • 3 days if normal vaginal delivery
  • 5 days if caesarean section
• For haemophilia B carrier, give replacement only if level noted to be < 50% – no need to monitor daily.

Topic Code: 5273