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How does CF affect the menstrual cycle? Why are sexual health and contraception important topics to discuss? And what does CF mean for fertility and pregnancy? Dr Kim Matthews shares her expertise on those questions and more.

Having spent years as an adolescent gynaecologist with an interest in fertility after a childhood illness, it has been my privilege to work with many families dealing with cystic fibrosis (CF).

As an adolescent gynaecologist, promoting normal menstrual function and treating difficulties in this area, discussing sexual function and promoting safe sex as well as contraception, and considering fertility options with safety as the priority would be the main areas of consultation.

CF and the menstrual cycle 

It is well recorded in the literature that both sexes with CF have a slow progression through puberty. Growth appears to be normal till 9 years of age even if the patient is malnourished but then we see an increasing disparity between chronological age, bone age, height, weight and BMI. The mean age of menarche in girls with CF is 14.4 years compared with 12.3 years in the general population with the associated growth spurt being delayed by 12 to 24 months. Irregular cycles are common (both short and long) and increase in incidence as forced vital capacity (FVC) reduces. Physically, low body weight and a decreased size in the uterus and ovaries can be seen on ultrasound.

Like all adolescence with menstrual irregularities, simple analgesic measures can be undertaken to treat the pain, tranexamic acid can be used to reduce the flow and cyclical progesterone or the combined OCP can be used to help regulate the cycles, or decrease the frequency of menses, as long it is safe for these medications to be used. Many young women with CF will have infrequent periods (or none at all) as their body fat composition is too low (less than 17%), which relates to the reduction in forced vital capacity (secondary amenorrhoea is common if FVC<55%), as well as possible central nervous system effects. If there is a risk of venous thromboembolism (VTE) the pill is contraindicated.

CF and sexual health

Whilst studies in the late 1980s reported that women with CF had reduced knowledge of sexual health and that few got married, it is pleasing to note that more recent studies show no differences between controls and CF patients in age of first intercourse, sexual health knowledge and the percentage in relationships which probably reflects the improved health of adolescence in both CF and the general population. This means that contraception and sexual health are important topics to be discussed for all young people visiting a health practitioner and what is recommended is guided by the general health of the individual. There is no contraindication to the use of cervical cancer vaccines in CF adolescents.

CF, fertility and pregnancy

The fertility potential of both men and women with CF is reduced and there are implications for the offspring. Virtually all men with CF are infertile due to congenital bilateral absence of the vas deferens (CBAVD) and although the effects in women are less clear, difficulties arise due to the increased thickened secretions in the tubes, cervix and vagina, as well as reduced follicle numbers, ovulation defects and increased incidence of follicular cysts. It is important to check the partner with a full CF screen to determine the potential risks of passing CF onto the offspring.

Equally important, the demands of pregnancy need to be considered prior to a pregnancy attempt to ensure safety for all involved. The first pregnancy was reported in 1960 but complications were very high. Careful planning with the respiratory team is therefore recommended with particular attention to cardiac and pulmonary lung function. Good lung function is the priority and maternal mortality and prematurity are associated with FVC <50% or if declining lung function is seen in the 6 months prior to pregnancy. If diabetes is present this will further complicate the pregnancy and its management. The nutritional aspects can be a challenge as an extra 300kcal/day to normal daily requirements are usually required and parenteral feeding may be necessary to meet these extra requirements.

A multidisciplinary approach prior and during the pregnancy and labour (including anaesthetists with experience in CF and high risk obstetrics) are essential and fertility management with the goal of a singleton pregnancy is the aim. Fertility management can range from simple measures to boost ovulation whilst being monitored to avoid a multiple pregnancy, intrauterine insemination to bypass the thick cervical mucous, through to IVF with a single embryo transfer and the use of preimplantation genetic diagnosis (PGD) to minimise the risk of CF in the offspring if this is appropriate after counselling and extensive consultation. The PGD process is a complex one and requires determining the exact genetic carrier status of the couple and developing a specific probe for this combination. Counselling is a required part of this process prior to proceeding and numerous embryos need to be developed and frozen whilst awaiting the PGD results. The aim is to transfer an appropriate single embryo to the uterus, thus bypassing the thick cervical mucous, and supporting any pregnancy that may result. The uterus is not a cave but a potential space and is prepared ready for embryo transfer at the appropriate time of the cycle. These embryos can also be used in a surrogacy situation if pregnancy is considered a contraindication for the mother with CF.

If it is the male partner who has CF, sperm can be obtained for a pregnancy attempt. This is usually via the surgical collection of sperm from the testes itself under local anaesthetic cover. The sperm can then be injected into the partner’s oocyte (egg) to form an embryo in a process known as intracytoplasmic sperm injection (ICSI) and the embryo transferred to the uterus after developing to the blastocyst stage. PGD is also a tool that can be equally employed under these circumstances.

So it is good to be aware of your individual circumstances and discuss it with your team. Planning for pregnancy is important with full discussion with all of your team. Be advised as to what is safe for you and what is not or what measures can be undertaken to improve your health prior to attempting pregnancy. Genetic health of the offspring should be considered and the fertility team is here to help should their services be required.

This article was first published in the CFCC Community Focus Magazine in November 2018 (4-5). It was republished on CFStrong in June 2021.