One in four IVF pregnancies is a twin birth. This research explored the impact of a multiple IVF birth on maternal mental health and examined whether twin status conferred additional risk for poor mother-infant interaction and parenting stress following a premature birth. It further surveyed factors which had influenced couples' decisions regarding embryo transfer. A prospective study of 175 mothers conceiving after IVF found mothers of multiples (n=56) had a three-fold risk of scoring above the threshold for depression in the postpartum period. Unsettled and irregular infant behaviour was another independent risk factor. Theme analysis revealed mothers of multiples were more likely to express negative themes such as 'tiredness'. More mothers of singletons described 'feeling wonderful'. Mothers of premature twins (n=17) were closely matched with mothers of premature singletons and compared using the Nursing Child Assessment Teaching Scale (NCATS), Home Observation for Measurement of the Environment (HOME) Responsivity subscale and the Parenting Stress Index. There were no differences in maternal NCATS scores but twin infants were less responsive and provided less clear cues. Mothers of twins were less responsive in an everyday setting and 25% (versus 0%) reported extreme levels of parenting stress. Singleton mothers had significantly lower scores for the parent child dysfunctional interaction subscale. None of the couples surveyed (n=68) had chosen to transfer a single embryo (eSET). Only 19.1% rated desire for twins as an important factor in their decision. Most important was desire to increase the chance of pregnancy (92.6%). Couples perceived eSET as reducing the chance of pregnancy. Most couples found the decision about number of embryos to transfer easy and rated medical advice as very important suggesting a need for more support for this complex decision. This thesis established that a single birth offers important psychosocial advantages for both mother and baby, findings which could promote informed decisions regarding embryo transfer.