Foetal premature atrial contractions during the second and third trimester are not associated with foetal breathing.

Foetal premature atrial contractions (PACs) are the most commonly encountered and also the most benign foetal arrhythmia. A retrospective cohort study was conducted with the objective to assess whether the presence of foetal breathing was associated with the presence of foetal PACs. A further objective was to evaluate whether this association would affect neonatal outcomes at a high volume referral centre. The diagnosis of PACs was based on the observation of a premature atrial contraction followed by a ventricular contraction on ultrasound myocardial M-mode. Trained ultrasonographers documented in the ultrasound report whether or not foetal breathing was present with PACs. 91 exams were identified, which included 75 individual pregnancies. Six women were identified who had foetal PACs associated with foetal breathing on ultrasound evaluation. Foetuses with PACs did not differ between the associated breathing and no-associated breathing groups with respect to maternal age, parity, mode of delivery, gestational age at delivery or birthweight. This study reaffirms that isolated PACs are a benign finding. Furthermore, it adds to the pool of literature on foetal PACs in that it is not associated with abnormal pregnancy outcomes regardless of the presence or absence of foetal breathing. Impact statement • What is already known on this subjectSince foetal breathing can effect Doppler ultrasound assessment of the foetal cardiovascular system, it is reasonable to consider that it may impact conditions such as foetal arrhythmias. • What the results of this study addFoetal breathing does not impact on the presence of premature atrial contractions. • What the implications are of these findings for clinical practice and/or further researchFoetal breathing is not associated with the finding of foetal premature atrial contractions.