BACKGROUND Despite the well established link between fetal macrosomia and maternal diabetes, it is estimated that 80% of macrosomic babies are born to mothers who are not hyperglycaemic Maternal obesity rather than diabetes proposed as a more important risk factor for increased birth weight In Northern Ireland babies born 4000g – 4499g account for around 12% of live births while >4500g around 2.3% (DHSSPSNI 2006) Fetal macrosomia is associated with serious outcomes for mother and baby and is linked with an increased risk of adolescent and adult obesity Previous studies examined different aspects of physical activity and diet separately without taking the whole lifestyle into account Future studies should be prospective, utilizing modern technology in the form of accelerometers to ensure that results are reliable, comparable and replicable in different populations AIMS To explore maternal energy balance during the third trimester of pregnancy and determine any relationship with fetal macrosomia To identify risk factors associated with fetal macrosomia in low risk pregnancies To examine the maternal and infant outcomes of pregnancies identified as at risk of fetal macrosomia To explore women’s perceptions and experiences of pregnancy and childbirth following delivery of a large for gestational age infant STUDY DESIGN INCLUSION CRITERIA weeks gestation; gestational age confirmed by USS or certain LMP Over 16 years of age Singleton pregnancy Have a reasonable standard of written and spoken English  Had a previous macrosomic baby OR  Fetal Abdominal Circumference above the 90 th percentile OR  Baby predicted to be >4000g at term  Study group only EXCLUSION CRITERIA Conditions which require extra care (based on Nice Guidelines 62, 2008), e.g. Diabetes, epilepsy, cardiac disease DATA COLLECTION TOOLS 4 Day Food Diary Physical Activity Monitor (SenseWear Armband) Venous blood sample - for batch analysis at end of study for factors related to the metabolic syndrome (e.g. serum lipids, growth factors) Data Collection Form: Antenatal information; Progress during pregnancy; Labour/Delivery/Neonatal Outcomes Interview schedule This study was funded by the Department of Employment and Learning (DEL) with additional funding from the Research and Development Office in Northern Ireland for equipment. Fetal Macrosomia : Physical Activity, Maternal Nutrition and Women’s Experiences E.W. Reid, J.A. McNeill, V.A. Holmes, F.A. Alderdice School of Nursing and Midwifery, Queens University Belfast METHODS The study employed a two phase, mixed methods approach utilizing a prospective cohort design and in depth interviews. Population: Low risk pregnant women predicted to deliver macrosomic babies (study group) or appropriate for gestational age (AGA) babies (control group). Phase 1: Participants wore a SenseWear® physical activity armband and completed a food diary (four consecutive days) in the third trimester of pregnancy. Demographic and obstetric data were collected from maternity records. Phase 2: Interviews were conducted at 3-4 months postpartum with a subgroup of women who delivered macrosomic babies, and analysed using content analysis. The Office for Research Ethics Committee for Northern Ireland (ORECNI) approved the study on 25/06/09 (Ref 09/NIR02/26). Women gave written informed consent and had at least 48 hours to review the patient information sheet. PHASE 1 RESULTS Of the 158 eligible referrals, 112 women participated in the study (71%). There was no significant difference in energy balance between groups. Women predicted to and who delivered macrosomic babies (≥4000g) spent significantly more time at very low levels of physical activity (<1 MET) than other women (p=0.007). Intake of PUFA n-3 was significantly higher in women who were predicted to deliver macrosomic babies but who subsequently delivered AGA babies at full term of this pregnancy (p=0.015). Women predicted to deliver macrosomic babies were more likely to be overweight (BMI> 25 kg/m²) at booking (p =0.017) and have attained third level education (p= 0.024). Predicted macrosomia was strongly associated with Caesarean section (p =0.010) compared with the control group (43% vs 22%). PHASE 2 RESULTS Four overarching themes emerged: Preparation for delivery Physical and emotional impact of macrosomia Professional relations Perceptions of macrosomia Findings highlighted the importance of communication with health professionals in relation to both prediction of macrosomia and decision making about delivery, and offers further understanding into the physical and emotional impact of having a macrosomic baby on women. CONCLUSIONS Findings from this study provide evidence that a more sedentary maternal lifestyle during the third trimester of pregnancy is associated with macrosomia and Further research is required in the form of intervention trials to clarify if increasing intensity of free living physical activity and reducing time spent in sedentary behaviour can prevent fetal macrosomia. This study has provided important insight into women’s experiences of macrosomia throughout the perinatal period and how they were influenced by previous birth experiences, professional relations and personal perceptions of macrosomia. Pregnant women at risk of having a macrosomic infant require extra support throughout the antenatal period continuing into the postnatal period, tailored to the woman’s information needs, perceived fears and anxiety, and with time allocated to discuss previous birth experiences and options for delivery. References Department Of Health And Social Services And Public Safety, Northern Ireland, Annual Report, [Homepage of DHSSPSNI], [Online]. Available: