Telangiectasia Self Help Group
FACT SHEET 4.
During pregnancy there are major changes in hormonal levels and blood flow. These combine to subject an expectant mother to a range of new symptoms – morning sickness, tiredness, faints and those funny food cravings. When the mother has HHT, a new range of concerns may arise: What will happen to my nosebleeds? What should I be worried about? Is there anything special my doctors and I should know? How will the baby be affected by my HHT?
This information fact sheet is designed to give you information as given to patients attending the Hammersmith Hospital HHT Clinic in London, England. We cannot advise you on whether you should or should not become pregnant (your own doctors are best placed for individual advice), but we can let you know how pregnancy might be different if you have HHT, and how to manage it as safely as possible.
Why should pregnancy affect HHT?
During pregnancy the circulating blood may increase by as much as 60%, which is normal and essential for the development of the baby. This means fragile blood vessels may be more prone to bleed. The body copes with this extra blood by making many of the mother’s blood vessels dilate, and these do not always return to their pre-pregnancy size. In spite of this, the majority of HHT pregnancies are safe for the mother with HHT and for the baby.
Are particular families more at risk of pregnancy-related complications?
You are probably aware that HHT affects members of you family in different ways, even though everyone with HHT in any one particular family will have the same genetic defect. This suggests that factors other than the mutated gene contribute to how HHT develops in any one individual, and this includes pregnancy-related complications.
When we looked at a series of 161 HHT pregnancies, 11 women had significant complications. Importantly, all except one of these women had close female relatives who had successful, uncomplicated pregnancies. The women belonged to eight different HHT families, with different genetic mutations, and there appeared to be nothing special about these families. So just because a family member has or has not suffered a complication does not mean that the same will happen to you.
HHT Pregnancy: The Facts
Will the baby be all right?
Two published reports have now shown that the miscarriage rate is comparable in HHT and non-HHT pregnancies. Obviously, on average, one-half of the babies born to an HHT mother (or father) will go on to develop HHT, but there is no evidence for additional abnormalities developing more commonly that in non-HHT pregnancies.
It is import to realise that even if pulmonary AVM’s (PAVM’s) have caused a very low blood oxygen level in the mother, the baby can still develop normally, though amongst the women in our series with the lowest oxygen levels, premature births of healthy but small babies were common. If you have low oxygen levels, your baby’s growth would probably be carefully watched by your obstetrician.
Will I be all right?
Most pregnancies result in no serious HHT-related complications for the mother. Nosebleeds usually get worse, and new telangiectases often develop, but some women actually report an improvement in nosebleeds, and new skin lesions often improve post pregnancy. There are four important considerations for you:
In women in whom pregnancy precipitates the growth of previously undetectable PAVMs, it is not know if these would have gone on to develop later in life, in the absence of pregnancy. Overall, women with HHT are more prone to PAVMs than men (on average, of 100 individuals with PAVMs due to HHT, 62 will be women and only 38 will be men). However, the excess of PAVMs in women could also reflect the effects of female hormones in the absence of pregnancy, as seen in other aspects of HHT: In some women, nosebleeds vary through the menstrual cycle and menopause, and Dr. Eric Cutsem has clearly demonstrated benefits of oestrogen-progesterone therapy in heavily transfusion-dependant patients. Avoiding pregnancy does not mean you will avoid PAVMs.
I have HHT and would like to have children. What should I do?
Adapted from an article originally published in HHT Foundation International Direct Connection Winter 1997, and updated August 2002.
This Pamphlet was prepared by Dr Claire Sholvlin, Senior Lecturer and Honorary Consultant Physician, Hammersmith Hospital and Imperial College, London. In conjunction with Dr James Jackson, Consultant Interventional Radiologist, Hammersmith Hospital, Professor Michael de Swiet, Consultant Obstetric Physician, Queen Charlotte’s and Chelsea Hospital and Dr Wendy Taylor, Consultant Interventional Neuroradiologist, London.