Leah said she kept quiet about her pregnancy to protect Rachel's happiness. (1.2.58)
Nowadays, women jump to their cellphones and text their friends and siblings right away about a pregnancy. But the bond between sisters in Jacob's family was complicated. Of course, they're kind of sharing a man and thinking about how they'll live the rest of their lives in Man's Land, so we're not surprised.
Attending her sister's births made her wish to become part of the great mother-mystery, which is bought with pain and repaid with an infant's sparkling smile and silken skin. (1.3.5)
The "great mother-mystery" is pretty much one of the focal points in this book. It's the stage in life at which giving birth can be a reward or a death sentence.
But I did not tell Joseph about the whispered conversations among the women. (2.2.31)
What happens in the red tent stays in the red tent—that's the agreement the women have with each other. Secrecy is important because the red tent is really the only thing that gives the women in power in this world; if the men knew everything about it, the women would be even more at their mercy.
She had been a woman just as my mother was a woman, and yet she was a creature totally unlike my mother. (2.2.59)
Dinah is referring to Ruti here. Yeah, unfortunately, the bond between women doesn't extend to all women. Ruti was like a "creature" to Jacob's wives—which means that status often trumps gender in this world.
In the red tent [...] women give thanks—for repose and restoration, for the knowledge that life comes from between our legs, and that life costs blood. (2.5.62)
Now, this takes the meaning of feminine to a whole new place: the women in The Red Tent redefine femininity: here, femininity is all about bravery and sacrifice.
For a moment, I weighed the idea of keeping my secret and remaining a girl, but the thought passed quickly. I could only be what I was. And I was a woman. (2.6.18)
Once Dinah becomes a woman, she can no longer be a girl—one quality of being a woman for Dinah is the responsibility of serving as a woman, not just as a child.
I laughed until my sides ached. I smiled until my face hurt. It was good to be a woman! (2.6.25)
Well, it's all well and good until she's giving birth.
Although I had stopped worshipping my mothers as perfect creatures, I looked forward to those days with them and the other women who bled. (2.6.42)
Yeah, that's right, folks: these women actually enjoy menstruation, as it gives them a chance to bond. That's one way to look at it.
In the space of his years, my body had taken its full shape and my heart had grown in wisdom, for I understood what it was to be a mother. (3.2.2)
Dinah is a girl, then a woman, and then a mother. This third stage is where she gains her wisdom. Why does motherhood change so much for her?
I searched for the brother I remembered, the playfellow who listened to the words of women with respect [...]. (3.5.58)
The fact that Dinah has to point out that Joseph used to treat women with respect shows how rare it was to find a man who respected women back then. (*cough* Just back then? *cough*)