Meg and Mave Carter are a pair of twins introduced in Series 2, Episode 3. They are both portrayed by Monica Dolan. They are commonly known by the moniker Meg'n'Mave.
Born when Sister Monica Joan was well enough to still practice midwifery, the Carter twins were born with Sister Monica Joan assisting. She can still recall the birth with perfect clarity, and remarks that Meg came first and screamed until her sister Mave was laid beside her "then both fell silent". However, Mave was born the wrong way around and caused her mother's haemorrhage and subsequent death.
Growing up, Meg and Mave were closer than average twins, even going as far to marry the same man. When Mave, the younger, more docile twin, got pregnant, Meg became very domineering, refusing to let Mave die in childbirth. Meg's medical expertise is only limited to medieval teachings, herbal teas, tarot card readings and outdated practices. Meg has no trust in modern medicine, believing modern maternity homes to be death traps. Fearful Mave can't bear to have her sister upset, and goes un-protesting with her choices, though it is clear she is unsure.
When Mave goes into labour, she has her husband call for the midwives, unknown to Meg. Trixie and Sister Bernadette rush to attend, alerting Dr. Turner who will also attend due to Mave's age and the fact that it's her first baby. Upon arrival, Meg tries to shove the women out, insisting they are not needed, but Mave calls out that she's the one who summoned them and for Meg to stand aside and let them do their jobs. Angry, Meg leaves the room. The baby comes easily enough, but Mave is exhausted and looks away from it, saying she wants her sister. When she next has a contraction, it is revealed that she is pregnant with twins and that the second baby is the wrong way around. When Dr. Turner tries to right the problem, causing Mave to scream in pain, Meg rushes in, shoving the doctor off and slapping Sister Bernadette across the face. Angrily, Dr. Turner rights himself and snaps at Meg to sit down and let them work so they can save her sister, and if she interferes again, it is a very real possibility that both mother and baby will die.
Meg holds Mave's hand as she gives birth to another baby girl, but haemorrhages immediately after. As Sister Bernadette works to get the baby to breathe, Dr. Turner aids Mave, and soon mother and baby are alright. Sister Bernadette gives the second baby to Mave and the first baby to Meg. Mave gives the care of the first baby to Meg and they decide to name their daughters Little Meg and Little Mave after each other.
In the last shot of the episode, Meg and Mave are revealed to have embraced modern medicine and attended the clinic with their daughters.