Born Again
After fleeing Wentworth Prison, Jamie and Claire hide out at the Abbey of Ste. Anne de Beaupré in France. Jamie is on the brink of death, and his wounds are deep, both physically and psychologically. The abuse and rape he suffered at the hands of Jonathan Randall was extreme, and as Jamie struggles to live, Claire confesses she's a time traveler to Father Anselm, and he believes her.
What follows is an epic lecture on fate versus free will. It seems that Claire is a combination of both… it was fated for her to travel back to this time period, but she has the free will to make choices and maybe or maybe not change the future. Claire worries about her every action affecting the future (what about Frank, her husband, who is Randall's descendant?), but Father Anselm takes some pressure off Claire when he tells her bluntly, "Everyone's actions affect the future" (40.132). Time travelers aren't the only ones who count, yo.
In order to heal Jamie, Claire pretends to be Randall (having been married to his descendant, she knows exactly what he's like) and taunts Jamie into attacking her. This is the only way she knows to heal him. He is scared to have sex with her after being raped by Randall, so by forcing him to have sex with her while she's pretending to be Randall (arguably one of the book's strangest moments), Claire proves that Jamie has the mental strength to overcome the pain he'd suffered.
In other words, the pain is a part of him. He doesn't have to hide from it, and Claire doesn't love him any less because of it.
After that, Claire and Jamie descend into the hot springs below the abbey. Previously, Claire welcomed Jamie into her womb, if you will, acting as both lover and mother to him to bring him back from the brink of despair. Jamie doesn't have a womb for her, so Claire finds comfort within the earth itself.
It's all very symbolic. In the hot springs, Claire hears "the infinitely slow beat of a great heart nearby" (41.104), and there she realizes that she is pregnant, even though she previously believed herself to be barren. At its heart, Outlander is just a really long romance story, and all romances need a happy ending. Insofar as wombs are original homes, this installment in the series ends with Jamie and Claire coming home to each other. Aw.