Fibroids are non-cancerous growths in the womb. They are very common affecting 20-40% of women during their reproductive ages. They are solid tumours that can be found in various parts of the womb. They may be solitary or multiple and may range in size from seedlings to gigantic tumours. Their effects on pregnancy is related to the size and location of the tumour.
Though not absolute, fibroids may reduce the chances of conception by a number of ways:
- Cervical changes: cervical fibroids may prolapse into the vagina or distort the shape of the cervix causing obstruction to the flow of sperm into the uterus.
- Uterine body/cavity changes: fibroids located on the body of the uterus (submucosal, subserosal, intramural) or within its cavity (intracavitary) may impact on conception by diverting the flow of blood from the uterine lining which in turn affects its ability to thicken and embed a fertilized egg. Gross changes in the shape of the uterus may also affect the movement of sperm or the fertilized egg.
- Fallopian tube changes: cornual fibroids may cause mechanical obstruction of the fallopian tubes preventing the fertilized egg from transiting to the fundus of the uterus where it should be implanted.
- Spontaneous abortion(miscarriage): multiplicity and certain locations of fibroids(uterine body, intramural and submucous) have been shown to be associated with the increased rate of miscarriage in fibroid.
- Bleeding: occurs especially if the site of the fibroid and implantation are contiguous.
- Placenta praevia: refers to abnormal site of implantation of placenta. This may occur as a result of fibroids occupying its normal position in the fundus of the uterus.
- Intrauterine growth restriction: huge fibroids may prevent the foetus from attaining maximum weigh/size due to decreased compartmental space.
- Abruptio placenta: sudden detachment of the placenta from the uterine wall. It occurs most commonly in submucosal fibroids and huge fibroids.
- Birth deformities: some birth deformities have been seen in women with huge fibroids and submucosal fibroids.
- Preterm labour: refers to the onset of labour before 37 weeks. It is mostly seen in multiple fibroids.
- Ruptured uterus following myomectomy/Caesarean delivery: after surgical removal of the fibroid, women whose endometrium was breached are advised to have elective Caesarean delivery because the frequent, regular and intense uterine contractions of labour may lead to rupture in the breached endometrium.
- Malpresentation: refers to abnormal positioning of the foetus at delivery.It is most common in multiple fibroids, huge fibroids and lower uterine segment fibroid.
- Post partum haemorrhage: refers to bleeding up to 48 hours after birth. It is a cause of maternal mortality. Fibroids may interfere with contractions of the uterus resulting to decreased uterine tone and bleeding.