Which career first?
Authors: Susan Bewley, Melanie Davies, Peter Braude
Journal: BMJ (2005)

Pregnancies in women older than 35 are increasing markedly in Western countries.1 Some commentators believe that this demographic shift poses a small or manageable problem as there are compensatory successful fertility treatments. However, it is harder for older women to become and stay pregnant, and outcomes for the mother and child are poorer.2-5

Age related fertility problems increase after 35 and dramatically after 40. Women have had more opportunity to acquire pelvic infections or develop endometriosis or premature menopause. Body mass index, which rises with age, independently affects fertility and treatment adversely. We do not understand reproductive senescence,w1 but there are no immediate prospects of treatments to reverse it. Paradoxically, the availability of in vitro fertilisation (IVF) may lull women into infertility while they wait for a suitable partner and concentrate on their careers and achieving security and a comfortable living standard. But this expensive, invasive treatment has high failure rates (more than 70% of women undergoing a cycle of IVF do not achieve a live birth—more than 90% when older than 40).6 It brings extra risks of multiple pregnancy as two—and in women older than 40, three—embryos can be transferred. Delaying also affects partnersw2: semen counts deteriorate gradually every year, and children of older men have an increased risk of schizophrenia and new mutation autosomal dominant disorders (such as achondroplasia and Marfan syndrome).

Once a woman is pregnant, age affects outcome adversely, with increased miscarriages,7 ectopic pregnancies, and twinning. Fetal and chromosomal abnormalities increase, which can result in difficult decisions and invasive testing (with associated miscarriages and terminations). Pregnancy diseases increase: preeclampsia, haemorrhage, preterm ruptured membranes, and placenta praevia, among others. Becoming pregnant later in life overlaps with the onset of chronic and life threatening diseases. Older mothers are more likely to be obese, take medication, have a medical disorder (arthritis, depression, cancer, or myocardial infarction), experience severe morbidity,w3 or die.8 Age, chronic hypertension, and pregestational diabetes are independent risk factors for intrauterine growth restriction. Inductions, dysfunctional uterine contractions, and abnormalities of the fetal heart rate are more common. Elective and emergency caesarean sections increase,9 carrying complications of bleeding, infection, thrombosis, later infertility, repeat caesarean, and placenta accreta.10 Prematurity, stillbirths, and neonatal deaths rise, as do admissions to neonatal intensive care. Animal models show differential effects of maternal age on brain development.w4 Programming hypotheses propose that small differences in the fitness of populations of mothers could cascade into larger disease effects in the next generation.w5

Health effects and social implications for the mother are complex, hard to research, and may be confounded by parity, contraception, education, and social class. Parenting (and grandparenting) when older provides mixed blessings: anxiety in pregnancyw6 and postnatal depression rise with agew7; later first pregnancy is associated with a higher risk of breast cancer but a lower risk of cervical cancerw8; the highest estimated risk due to all cause mortality is seen among women who give birth in their 40s.w9 Modest improvements in school attainment and maturer parentingw10 might, however, offset the inevitable effects of diminished fitness, illness, and bereavement.

For individual women, a short delay poses little absolute risk. Most pregnancies in women older than 35 have good outcomes, but small shifts in population distribution curves affect large numbers of women. Obstetricians and gynaecologists have seen dramatic changes in two decades alongside this demographic transformation and are witnesses to the resultant tragedies. The pain of infertility; miscarriage; smaller families than desired; or damage to pregnancy, mothers, and children is very private, particularly when women blame themselves for choices made without being fully aware of the consequences. It is ironic that as society becomes more risk averse and pregnant women more anxious than in the past, a major preventable cause of this ill health and unhappiness is unacknowledged. Public health agencies target teenagers but ignore the epidemic of pregnancy in middle age.

Medicine, just as other careers, is chosen by many women although they are still under-represented at the top. The especially long education, training, and competitive career ladders cause many women to defer childbearing. Doctors need to be aware of the risks for themselves and for their patients, as they are ideally placed to inform women about reproductive choices. Women want to “have it all,” but biology is unchanged11; deferring defies nature and risks heartbreak. If women want room for manoeuvre they are unwise to wait till their 30s. Their delays may reflect disincentives to earlier pregnancy or maybe an underlying resistance to childbearing as, despite the advantages brought about by feminism and equal opportunities legislation, women still bear full domestic burdens as well as work and financial responsibilities.12

The reasons for these difficulties lie not with women but with a distorted and uninformed view from society, employers, and health planners. No serious research is being undertaken into the additional costs to the NHS, the increased load on maternity services (whose constraints are already under the Healthcare Commission's scrutiny) and neonatal units,13 the extra costs to employers of later maternity leave (where higher salaries act as a perverse incentive for women to delay), or considerations of means that enable women to have children earlier. Free choices cannot be made with partial knowledge, economic disadvantage for mothers, and unsupportive workplaces. Doctors and healthcare planners need to grasp this threat to public health and support women to achieve biologically optimal childbearing.