Monica and/or Alice likes the idea of having a living being growing inside of her.
Monica & Alice love kids and babies.
Neither Alice nor Monica particularly want children, but everyone around them is desperate for them to have a child.
Alice and Monica don't want kids, but their neighbors Bob and Carl do.
Alice initially wants a child, but after much tension and a heartfelt conversation with Monica, decides against it.
Alice wants a child, but Monica doesn't.
They think they want a child; but once they get one, it turns out to be a pain in the ass.
Alice changes her mind again, and realizes she does want children after all.
Monica changes her mind.
..but they think it was all worth it.
After thinking about it for some time, Monica suddenly starts to want a kid.
Alice and Monica are so desperate for a child that they actively conspire to acquire 'samples' from their male friends and acquaintances by any means necessary. Neither appears to have considered adoption or a sperm bank.
Alice and Monica both want kids but decide to get a dog as a trial child. After much havok with the dog, they decide they'd rather seek fulfillment in another way.
Zig Zagged: Alice and Monica flipflop wildly over the issue of children in their relationship.
Averted: Neither Alice nor Monica expresses any particular or notable desire for children.
The writer doesn't really have a deep understanding of lesbianism or lesbian women, and throws in a pregnancy plotline because they feel that children are something all women ultimately want at some point.
The writer is a lesbian, and is basing the story around her and her partner's desires for and experiences in conceiving a child.
Lampshaded: "Don't tell me you want to talk about the whole kids' thing again..."
Invoked: The first question Alice asks any potential partner is what their thoughts on having children would be like.
Defied: Alice and / or Monica dislike children and agree not to have any.
Discussed: Once Alice and Monica become a couple, they joke about how they better start angsting about their difficulties with getting children, since that's what's happened in the books they've read.
Conversed: A character reading a lesbian-themed novel comments on how every author who tackles lesbianism seems to focus on motherhood as well.
Deconstructed: Alice and Monica's desire for children stems from insecurity over their relationship and / or homosexuality, and they feel that doing a 'normal' thing like having children will solidify their relationship.
Reconstructed: Alice and Monica confront and resolve their doubts and insecurities, but still decide that they'd like to have a child together.
Played For Laughs: Alice and Monica both want to get pregnant and don't mind doing so the old fashioned way. There are plenty of men that have no problem with one night stands and consider a menage a trois even better. Everybody wins!
Played For Drama:
Alice desperately wants a child, Monica is less certain. This creates tension in their relationship.
Alice's desires for a baby lead her to engage in sexual intercourse with men, which creates confusion for her regarding her sexual identity. Monica, for her part, isn't impressed when she learns that Alice has reduced to cheating on her to sate her desires for a family.
Alice and Monica aren't Bi, they're clearly gay. Doing it the old fashioned way is messy but cheap. The nervous pair pretend to want a threesome, so they can support each other through the act. The whole episode revolves around Alice and Monica struggling through their anxieties in a way that strengthens their love.