During Ramadan, pregnant Muslim women commonly fast during daylight hours, abstaining from food and drink. This pattern of maternal intermittent fasting (IF) has been reported to reduce birthweight and placental weight, with gender-related adverse impacts on health later in adulthood (van Ewijk, 2011). Here, a rat model mimicking IF during pregnancy was employed to investigate gender-related outcomes. Food was withdrawn daily from pregnant dams between 5 pm to 9 am from day 1 (D1; day plug was found) to D21 of gestation. Control dams received food ad libitum and both groups had free access to water. All measurements were performed at D21. Fetuses and placentas were weighed; gender was determined by PCR for male-specific sex determining region Y gene. Rats were anaesthetised with inhaled isoflurane (4% in oxygen at 2L min-1) and sodium thiobutabarbital (100mg kg-1 i.p.) and unidirectional maternofetal clearance of 14C-methylaminoisobutyric acid (14C-MeAIB) (MeAIBKmf) measured to determine system A amino acid transport across the intact placenta in vivo (Kusinski et al., 2011). All data are presented as mean±SEM with (n)=no. litters or individual fetuses (MeAIBKmf only).Maternal weight gain (n=15) was significantly lower in IF group (control 133±6g, IF 94±6g; P<0.0001 (unpaired t test)) with no difference in litter size between groups. IF fetal and placental weights were significantly reduced accompanied by reduced fetal/placental weight ratio and MeAIBKmf in both genders (Table 1).These data demonstrate that IF negatively affects maternal weight gain over pregnancy, associated with reduced fetal and placental weights for both genders. Fetal/placental weight ratio (a proxy of placental transport efficiency) was diminished, consistent with the reduced MeAIBKmf observed for both genders in IF group. This study shows that IF has profound impacts on fetal and placental development and that impairment of fetal growth may be underpinned by compromised placental amino acid transport common to both genders.