Abortion is deﬁned as the expulsion of a FETUS before it is normally viable, usually before 24 weeks of pregnancy. (There are exceptional cases nowadays in which fetuses as young as 22 weeks’ gestation have survived.) (See also PREGNANCY AND LABOUR.)
Spontaneous abortion Often called miscarriage, this may occur at any time before 28 weeks; 85 per cent occur in the ﬁrst 12 weeks of pregnancy. Of all diagnosed pregnancies, 25 per cent end in spontaneous abortion.
Spontaneous abortions occurring in early pregnancy are almost always associated with chromosomal abnormalities of the fetus. Other causes are uterine shape, maternal disorders such as DIABETES MELLITUS, diseases of the thyroid gland (see under ENDOCRINE GLANDS), and problems with the immune system (see IMMUNITY). Recurrent spontaneous abortion (that is, three or more) seems to be a particular problem in women who have an abnormal response of their immune system to pregnancy. Other factors include being older, having had a lot of babies previously, cigarette smoking and spontaneous (but not therapeutic) abortions in the past.
Early ULTRASOUND scans have altered the management of spontaneous abortions. These make it possible to distinguish between threatened abortion, where a woman has had some vaginal bleeding but the fetus is alive; inevitable abortion, where the neck of the uterus has started to open up; incomplete abortion, where part of the fetus or placenta is lost but some remains inside the uterus; and complete abortion. There is no evidence that bed rest is eﬀective in stopping a threatened abortion becoming inevitable.
Inevitable or incomplete abortion will usually require a gynaecologist to empty (evacuate) the uterus. (Complete miscarriage requires no treatment.) Evacuation of the uterus is carried out using local or general anaesthetic, usually gentle dilatation of the neck of the uterus (cervix), and curetting-out the remaining products of the pregnancy.
A few late abortions are associated with the cervix opening too early, abnormal structural abnormalities of the uterus, and possibly infection in the mother.
Drugs are often used to suppress uterine contractions, but evidence-based studies show that these do not generally improve fetal salvage. In proven cases of cervical incompetence, the cervix can be closed with a suture which is removed at 37 weeks’ gestation. The evidence for the value of this procedure is uncertain.
Therapeutic abortion In the UK, before an abortion procedure is legally permitted, two doctors must agree and sign a form deﬁned under the 1967 Abortion Act that the continuation of the pregnancy would involve risk – greater than if the pregnancy were terminated – of injury to the physical and/or mental health of the mother or any existing child(ren).
Legislation in 1990 modiﬁed the Act, which had previously stated that, at the time of the abortion, the pregnancy should not have exceeded the 24th week. Now, an abortion may legally be performed if continuing the pregnancy would risk the woman’s life, or the mental health of the woman or her existing child(ren) is at risk, or if there is a substantial risk of serious handicap to the baby. In 95 per cent of therapeutic terminations in the UK the reason is ‘risk of injury to the physical or mental health of the woman’.
There is no time limit on therapeutic abortion where the termination is done to save the mother’s life, there is substantial risk of serious fetal handicap, or of grave permanent injury to the health of the mother.
About 190,000 terminations are carried out in the UK each year and only 1–1.5 per cent are over 20 weeks’ gestation, with the vast majority of these late abortions being for severe, late-diagnosed, fetal abnormality.
The maternal mortality from therapeutic abortion is less than 1 per 100,000 women and, provided that the procedure is performed skilfully by experienced doctors before 12 weeks of pregnancy, it is very safe. There is no evidence that therapeutic abortion is associated with any reduction in future fertility, increased rates of spontaneous abortion or preterm birth in subsequent pregnancies.
Methods of abortion All abortions must be carried out in premises licensed for doing so or in NHS hospitals. The method used is either surgical or medical, with the latter being used more and the former less as time goes on. Proper consent must be obtained, signed for and witnessed. Women under 16 years of age can consent to termination provided that the doctors obtaining the consent are sure she clearly understands the procedure and its implications. Parental consent in the under-16s is not legally required, but counselling doctors have a duty to record that they have advised young people to inform their parents. However, many youngsters do not do so. The woman’s partner has no legal say in the decision to terminate her pregnancy.
MEDICAL METHODS A combination of two drugs, mifepristone and a prostaglandin (or a prostaglandin-like drug, misoprostol – see PROSTAGLANDINS), may be used to terminate a pregnancy up to 63 days’ gestation. A similar regime can be used between nine and 12 weeks but at this gestation there is a 5 per cent risk of post-treatment HAEMORRHAGE.
An ultrasound scan is ﬁrst done to conﬁrm pregnancy and gestation. The sac containing the developing placenta and fetus must be in the uterus; the woman must be under 35 years of age if she is a moderate smoker, but can be over 35 if she is a non-smoker. Reasons for not using this method include women with diseases of the ADRENAL GLANDS, on long-term CORTICOSTEROIDS, and those who have a haemorrhagic disorder or who are on ANTICOAGULANTS. The drugs cannot be used in women with severe liver or kidney disease, and caution is required in those with CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD), disease of the cardiovascular system, or prosthetic heart valves (see PROSTHESIS), as well as with those who have had a CAESAREAN SECTION or an ECTOPIC PREGNANCY in the past or who are being treated for HYPERTENSION.
Some clinics use this drug combination for pregnancies older than 12 weeks. In pregnancies approaching viability (20 weeks), pretreatment fetocide (killing of the fetus) with intrauterine drug therapy may be required.
SURGICAL METHODS Vacuum curettage is a method used up to 14–15 weeks. Some very experienced gynaecologists will perform abortions surgically by dilating the cervix and evacuating the uterine contents up to 22 weeks’ gestation. The greater the size of the pregnancy, the higher the risk of haemorrhage and perforation of the uterus. In the UK, illegal abortion is rare but in other countries this is not the case. Where illegal abortions are done, the risks of infection and perforation are high and death a deﬁnite risk. Legal abortions are generally safe. In the USA, partial-birth abortions are spoken of but, in fact, there is no such procedure recorded in the UK medical journals.