The majority of women do not meet the recommended levels of exercise during their pregnancies, frequently due to a lack of time. High-intensity interval training offers a potential solution, providing an effective, time-efficient exercise modality. This exercise modality has not been studied in pregnancy therefore, the objective of this study was to evaluate fetal response to a high-intensity interval training resistance circuit in the late second and early third trimesters of pregnancy. Fourteen active, healthy women with uncomplicated, singleton pregnancies participated in a high-intensity interval training resistance circuit between 28+0/7 and 32+0/7 weeks. A Borg rating of perceived exertion of 15-17/20 and an estimated heart rate of 80-90% of maternal heart-rate maximum was targeted. Fetal well-being was evaluated continuously with fetal heart-rate tracings and umbilical artery Doppler velocimetry conducted pre-and post-exercise. Fetal heart rate tracings were normal throughout the exercise circuit. Post-exercise, umbilical artery end-diastolic flow was normal and significant decreases were observed in the mean systolic/diastolic ratios, pulsatility indexes and resistance indexes. Therefore, in a small cohort of active pregnant women, a high-intensity interval training resistance circuit in the late second and early third trimesters of pregnancy appears to be a safe exercise modality with no acute, adverse fetal effects but further study is required. Novelty: • High-Intensity Interval Training, at an intensity in excess of current recommendations, does not appear to be associated with any adverse fetal effects in previously active pregnant women. • High-Intensity Interval Training is an enjoyable and effective exercise modality in previously active pregnant women.

Although still rare, the incidence of cesarean scar ectopic pregnancies has increased in the past few years due to the number of cesarean section deliveries being performed. If left untreated, this can have devastating complications for patients, including hemorrhage, uterine rupture, and maternal death. Occurrence of cesarean scar ectopic is about 1 in 2000 pregnancies. Most of these pregnancies have a normal rising beta-human chorionic gonadotropin (beta-hCG), and patients may present asymptomatic, with light spotting during early first trimester and with or without cramping. Due to rarity, there is very minimal awareness among sonographers of the likelihood of cesarean scar ectopic, which can be misdiagnosed as cervical pregnancy or spontaneous abortion in progress. Ultrasound is the primary imaging modality and plays a very important role in recognizing and providing proper early diagnosis.