The launch trailer for the new season of Call the Midwife has been released.

The medical period drama’s sixth season will begin at 8pm on Sunday 22 January on BBC One, following last month’s feature-length Christmas special.

In the first of eight new episodes, the midwives receive a rapturous welcome when they return from their South African adventure – but all is not well at Nonnatus House.

Watch the Season 6 trailer…

The official synopsis for Episode 1 reads: “In their absence, Sister Ursula has been running a very tight ship and it is quickly announced that she will remain in charge at Nonnatus House, above Sister Julienne.

“Sister Ursula makes unpopular changes, but bound by a vow of obedience Sister Julienne is unable to challenge her. As the Nonnatuns chafe under the new rules, the midwives are drawn into helping heavily pregnant mother Trudy Watts, whose husband has just been released from prison for extortion.

“Gradually, the problems below the surface of the marriage become clear: a victim of domestic abuse Trudy is desperate for a divorce but risks losing her home, her good name and crucially, access to her children. Trapped and with no clear way out, Trudy’s suffering sends shock waves through Nonnatus House, most noticeably affecting Sister Mary Cynthia who is suffering with increasing anxiety following her recent attack.

“Elsewhere, Shelagh is harbouring a secret and struggles to tell Dr Turner, and Patsy receives some distressing news about her father in Hong Kong.”

The BBC announced last November that Call the Midwife will run for at least nine seasons, confirming Season 7, Season 8 and Season 9. The commission consists of eight 60-minute episodes in each season, plus three more Christmas specials.

Call the Midwife launched in 2012 and continues to be the most watched drama series in the UK, with all five seasons so far averaging around 10 million viewers per episode.

Buy the complete Season 1-5 box set on Amazon here.

Call the Midwife writer Heidi Thomas has promised “new challenges and new triumphs” in the sixth season.

Are you looking forward to the return of Call the Midwife? Let us know below…