How we cite our quotes: (Part.Chapter.Paragraph)
Quote #4
Then, a shy, embarrassed look came on her face. She explained that we might very well become young ladies while we were at school this year. She went through a most tangled-up explanation about the how and why, and finished by saying if we should start our complications, we should come see her. This time she didn't ask if there were any questions. (1.2.39)
Poor Sor Milagros obviously doesn't have much training in giving the girls the sex talk. When she talks about "complications" she means starting menstruation. The lack of dialogue or even proper terminology just signals how uncomfortable everyone is with this icky icky body stuff.
Quote #5
When she left, Sinita asked me if I understood what on earth Sor Milagros had been talking about. I looked at her surprised. Here she'd been dressed in black like a grownup young lady, and she didn't know the first thing. Right then, I told Sinita everything I knew about bleeding and having babies between your legs. She was pretty shocked, and beholden. (1.2.41)
Sinita is dressed in black because she is mourning her brother's death. This was a tradition kept only by women, not children, so her mourning clothes make her seem like a mature young lady. That's why Minerva is surprised that this seemingly mature girl has no idea what it means to be a woman, biologically speaking.
Quote #6
I lifted the covers, and for a moment, I couldn't make sense of the dark stains on the bottom sheet. Then I brought up my hand from checking myself. Sure enough, my complications had started. (1.2.82)
On the same night that she learns Trujillo's secret (that he's having everyone killed), Minerva gets her "complications." The term is Sor Milagros' clumsy word for her period. So in one night Minerva has grown up in the sense of hitting puberty and also having her eyes opened to the political reality of her country. "Complications" turns out to have a double meaning.