Fibroids and pregnancy: risks and management
In brief
Fibroids and pregnancy: the vast majority of pregnancies with a fibroid (uterine myoma) proceed normally: a systematic review published in the American Journal of Obstetrics and Gynecology concludes that good maternal and neonatal outcomes can be expected. The effect on fertility depends mainly on the position of the fibroid: those that distort the uterine cavity (submucosal) reduce the chances of an ongoing pregnancy by about half, whereas fibroids located under the serosa have no proven effect. According to French guidelines, removal of a submucosal fibroid is offered to women planning a pregnancy, but surgery on an intramural fibroid does not improve fertility.
Does a fibroid prevent you from getting pregnant?
Not necessarily. It all depends on where it lies in relation to the uterine cavity, as described by the FIGO classification (types 0 to 8).
| Type of fibroid | Location | Effect on fertility |
|---|---|---|
| Submucosal (FIGO 0, 1, 2) | Protrudes into the uterine cavity | Unfavourable: fewer ongoing pregnancies, mainly due to failure of embryo implantation |
| Intramural (FIGO 3, 4) | Within the thickness of the muscle | Debated effect, probably modest, more marked if large or close to the cavity |
| Subserosal (FIGO 5, 6, 7) | Towards the outside of the uterus | No proven effect |
In the review by Klatsky et al. (2008), submucosal fibroids were associated with an ongoing pregnancy rate about half as high (odds ratio 0.5). For intramural fibroids, cumulative pregnancy rates were slightly lower (36.9% versus 41.1%), a difference the authors consider partly due to bias in the studies.
A fibroid is rarely the only explanation for difficulty conceiving. It is therefore considered as part of a complete fertility work-up for the couple, which also looks for other causes (ovulation, fallopian tubes, semen analysis, ovarian reserve).
Should a fibroid be removed before pregnancy?
Submucosal fibroid (types 0 to 2): for women wishing to conceive, French guidelines recommend hysteroscopic resection when it measures less than 4 cm, whether or not it causes symptoms, and whether the pregnancy is spontaneous or achieved through assisted reproduction. The procedure is performed through the natural passages, with no scar on the uterine muscle.
Intramural fibroid (types 3 and 4): according to the same guidelines, it has a negative effect on fertility, but removing it does not improve the chances of pregnancy. Myomectomy is therefore only offered if it causes symptoms (bleeding, pain, compression), taking into account the consequences of the uterine scar for a future pregnancy.
Subserosal fibroid: in the absence of symptoms, there is no indication to operate for fertility reasons.
After recurrent miscarriages, the French guidelines on pregnancy loss suggest correcting an acquired abnormality of the uterine cavity (polyp, fibroid, adhesions) after three early or late miscarriages.
In all cases, the decision takes into account age, ovarian reserve and the healing period that surgery would require before trying to conceive. When age or ovarian reserve limit the time available, delaying pregnancy for surgery of uncertain benefit may be unfavourable.
What happens to a fibroid during pregnancy?
Under the effect of pregnancy hormones, a fibroid may increase in size, especially in the first trimester, but many remain stable and some shrink. It is not possible to predict its course precisely.
The fibroid is monitored during the usual pregnancy scans: its size, its position in relation to the placenta and the cervix, and its effect on the baby's presentation. How often it is monitored is tailored to each situation.
As a rule, a fibroid is never removed during pregnancy, except in exceptional circumstances (a twisted pedunculated fibroid, for example), because of the high risk of haemorrhage.
What is red degeneration (aseptic necrobiosis) of a fibroid?
This is the most typical complication of a fibroid during pregnancy. The fibroid grows faster than its blood vessels: part of its tissue lacks oxygen and dies, without infection (hence the term "aseptic").
It shows up as:
- localised pain, often intense, over the fibroid;
- sometimes a mild fever;
- sometimes uterine contractions.
It most often occurs during the second trimester. Treatment is based on rest and pain relief suitable for pregnancy; anti-inflammatory drugs (NSAIDs, such as ibuprofen) must only be taken on prescription and must not be used from the 6th month, even as a single dose (see medicines in pregnancy). Ultrasound makes it possible to identify the fibroid concerned and rule out other causes of pain. The episode usually settles within a few days.
Does a fibroid increase the risk of miscarriage or complications?
Obstetric complications related to fibroids are possible but remain uncommon. The review by Klatsky et al. reports, in women with fibroids:
| Event | Reported result |
|---|---|
| Miscarriage (intramural fibroids) | 20.4% versus 12.9% without fibroids |
| Abnormal presentation of the baby (breech, transverse) | Risk multiplied by about 2.9 |
| Caesarean section | Risk multiplied by about 3.7 |
| Preterm birth | Risk multiplied by about 1.5 |
| Dystocia (labour that does not progress) | 7.5% |
The authors stress that these risks also reflect the older age of women with fibroids and other differences between the populations studied. Other complications have been described: bleeding from a placenta implanted in contact with a fibroid, and growth restriction when a large fibroid occupies the cavity.
Can you have a vaginal birth with a fibroid?
Yes, in most cases. A fibroid alone does not justify a caesarean section. A caesarean is considered when:
- a fibroid located in the lower part of the uterus or on the cervix obstructs the baby's passage ("praevia" fibroid);
- the baby is in a breech or transverse position, partly because of the fibroid;
- a previous myomectomy has left a deep uterine scar, in which case the mode of delivery is discussed case by case.
The fibroid is not usually removed during a caesarean section, as the risk of bleeding is significant. After the birth, there is an increased risk of postpartum haemorrhage (the uterus contracts less well): the team is informed and takes appropriate preventive measures.
Pregnancy follow-up and the birth can take place at Maternité Sainte-Félicité (Paris 15th) or Clinique Sainte-Thérèse (Paris 17th).
And after a myomectomy or embolisation?
After a myomectomy in which the uterine muscle was opened, pregnancy is possible after a healing period. The operation report is important: it specifies the depth of the scar, which guides the choice of mode of delivery. The risk of uterine rupture is rare but justifies particular vigilance.
After uterine artery embolisation, pregnancy remains possible, but data on fertility are fewer and less reassuring than for myomectomy. French guidelines reserve embolisation for women who do not wish to become pregnant. This point is covered in detail in the article comparing myomectomy and embolisation.
When should you seek urgent care?
During a pregnancy with a fibroid, seek medical advice promptly or call 15 (SAMU) or 112 in France, or your local emergency number, in the event of:
- intense abdominal pain or pain that does not respond to simple painkillers;
- vaginal bleeding, however light;
- regular contractions before 37 weeks of amenorrhoea;
- fever;
- leakage of fluid or reduced baby movements.
Frequently asked questions
Will my fibroid grow during pregnancy?
It is possible, especially in the first trimester, but not systematic: many fibroids remain stable. Ultrasound monitoring makes it possible to follow its course.
Is the fibroid dangerous for my baby?
In the vast majority of cases, no. Complications (abnormal presentation, prematurity) are more frequent than in the absence of a fibroid but remain in the minority.
Should a small fibroid found during a fertility work-up be removed?
It depends on its position. A fibroid that distorts the cavity is generally removed by hysteroscopy; a small intramural or subserosal fibroid without symptoms is usually left in place.
Can I have IVF with a fibroid?
Yes. A submucosal fibroid is generally removed before embryo transfer; other fibroids do not systematically delay treatment.
Does the fibroid disappear after the birth?
It often shrinks in the months that follow, but rarely disappears. A follow-up scan allows the situation to be reassessed later on.
References
- Klatsky PC, et al. Fibroids and reproductive outcomes: a systematic literature review from conception to delivery. Am J Obstet Gynecol, 2008. doi:10.1016/j.ajog.2007.12.039 — PMID 18395031
- Marret H, et al. Therapeutic management of uterine fibroid tumors: updated French guidelines. Eur J Obstet Gynecol Reprod Biol, 2012. doi:10.1016/j.ejogrb.2012.07.030 — PMID 22939241
- Huchon C, et al. Pregnancy loss: French clinical practice guidelines. Eur J Obstet Gynecol Reprod Biol, 2016. doi:10.1016/j.ejogrb.2016.02.015 — PMID 27039249
Dr Olivier KadochObstetrician-gynaecologist and gynaecological surgeon in Paris (16th and 5th arrondissements). Former chef de clinique-assistant (senior registrar) at the Paris public hospitals (AP-HP); individually accredited by the French National Authority for Health (HAS). RPPS 10003957809. Background and practice locations
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