Depression is common in women of childbearing age. One large systematic review found a period prevalence for major depression of 12.7% across the 9 months of pregnancy and 7.1% in the first three months postnatally .
There has been considerably more research on postnatal depression and its consequences than on antenatal depression but the latter can also have adverse effects on both mother and baby. Women who experience perinatal depression are more likely to have a poor couple relationship, to self-harm [2–4], and it can affect the developing child independently of the occurrence of postnatal depression [5–8]. Antenatal depression has an impact on neonatal development through several mechanisms. Women who are depressed during pregnancy are more likely to smoke cigarettes, use alcohol and other illicit substances [9, 10], to experience preeclampsia and other obstetric complications [11, 12]. The consequences of these to the developing foetus may include low birth weight, preterm delivery, and reduced motor activity [13–17].
Many of those depressed in pregnancy do not recover and depression continues postnatally. One study found that 50% of women with high depression scores at 2 months postnatally had high depression scores at 32 weeks antenatally . Some of the consequences attributed to postnatal depression could therefore be due to antenatal depression. Identification and treatment of depression at this time has therefore become a health service priority and has been recommended in National treatment guidelines in the UK (NICE ) .
There have been a number of studies which have shown psychological and psychosocial treatments to be effective in improving mood postnatally [19–21]. In contrast, there have been few studies on the treatment of antenatal depression that aim to improve depression before the end of pregnancy and only one small trial using interpersonal therapy . Although there are a number of other studies that begin during pregnancy [23, 24] their primary aim is to prevent postnatal depression and other adverse postnatal outcomes rather than to successfully treat depression before the end of pregnancy.
The antenatal period provides a unique opportunity to identify and treat depression, as there is contact with general practitioners (GPs) and midwives from the first trimester, and there may be fewer practical barriers to treatment at this time, compared to postnatal depression when the mother has a young infant to care for. If the consequences for child development are to be prevented, then treatment needs to be prompt in order to improve mood before the end of pregnancy.
The choice of intervention in pregnancy is complicated by the need to consider the foetus as well as the mother. Guidance in the UK for treating antenatal depression recommends cognitive behavioural therapy (CBT) or interpersonal therapy (IPT) for severe or moderate depression in those with a previous history. Although the efficacy of CBT in the treatment of depression has been established outside the antenatal period, the effectiveness and feasibility of this approach and implementing it within the healthcare system during pregnancy is unknown. There are several reasons why this extrapolation to pregnancy, of treatments that are effective at other times, is inadequate. First, the risk benefit ratio for antidepressant treatment differs at this time [25, 26]. There are known adverse consequences for the developing foetus of some antidepressants [27, 28], an association with a lower gestational age at birth and an increased risk of preterm birth  and the acceptability of pharmacological treatment during pregnancy is lower . Therefore the consequence of this is that fewer women are using antidepressants during pregnancy than any other time therefore CBT is more likely to be delivered in the absence of antidepressants whilst the efficacy of this is known the effectiveness in this context is unknown. Second, the context in which the treatment is offered is different. There is an assumption that standard CBT approaches will work but some adaptations in content and delivery are needed. There are unique demands to a pregnant woman’s time, attention and energy, which may have an impact on the delivery of CBT. There are particular concerns during this period such as pregnancy specific worries and rumination is heightened along with interpersonal and social support needs . Finally, there is a more urgent need to provide a timely intervention as a delay, could compromise any benefits there may be on foetal development.
With this in mind we conducted a pilot RCT to assess the feasibility for a large-scale RCT of individual CBT in the treatment of depression by the end of pregnancy by piloting procedures for recruitment, assessment and randomisation to treatment, and the delivery of up to 12 sessions of CBT before the end of pregnancy. Data collection procedures were also piloted and included an assessment of the most appropriate way of collecting health care resource use for this population.