Main outcome measures

A patient focus group was consulted to design the questionnaire, together with input from the specialist mitochondrial clinical team. Four main outcome measures were selected for this study:

Fetal loss: miscarriage – spontaneous loss of pregnancy before 24 weeks of gestation; stillbirth – baby delivered with no signs of life at or after 24 weeks of gestation

Pregnancy‐related complications: gestational diabetes mellitus (GDM); hypertension; breathing difficulties (feeling of excessive breathlessness during pregnancy); anaemia; and antepartum vaginal bleeding

Mode of delivery: normal vaginal delivery; assisted vaginal delivery with forceps or vacuum; emergency and elective caesarean section

Newborn outcomes: gestational age; birthweight; preterm birth (<37 completed weeks of gestation); very preterm birth (<32 completed weeks of gestation); birth centiles – using customised centile calculations from NHS Gestation Network;11 admission to Special Care Baby Unit (SCBU); neonatal resuscitation.

These measures were self‐reported so cannot be precisely defined. They are the individual impressions of the respondents. The questionnaire was not piloted nor validated but feedback on clarity and feasibility was provided by a small group of five patients.