Give Me Your Hand by Megan Abbott

I never read anything by Megan Abbott but have been reading about her and her books for some time. I liked this page-turner.  I am going to try some other books by Abbott.
Here is a synopsis:

Kit Owens harbored only modest ambitions for herself when the mysterious Diane Fleming appeared in her high school chemistry class. But Diane's academic brilliance lit a fire in Kit, and the two developed an unlikely friendship... until Diane shared a secret that changed everything between them. More than a decade later, Kit thinks she's put Diane behind her forever, and she's begun to fulfill the scientific dreams Diane awakened in her. But the past comes roaring back when she discovers that Diane is her competition for a position both women covet: taking part in groundbreaking new research led by their idol. Soon enough, the two former friends find themselves locked in a dangerous game of cat-and-mouse that threatens to destroy them.

The Perfect Mother by Aimee Molloy

This book came to my attention on Kirkus, I think, as a great summer read. 

I did enjoy it and read it quickly.  The story revolves around a group of new moms living in Brooklyn and the camaraderie they enjoy as part of the May Mothers.  While it is in essence, a psychological thriller and whodunit, it explores the feelings and insecurities of this group of very different young women and the way they deal with early motherhood.
Here is a review from Booklist Review:

Molloy's fiction debut features the May Mothers, a mommy group made up of Brooklynites who gave birth in the same month. One mother, Winnie, seems to always be on the outskirts of the group. She's quite reserved, so the more gregarious mothers have to push her to join them in a Mom's Night Out at a local bar. She frets momentarily over leaving her three-month-old son, Midas, but aggressive Nell sets her up with a new babysitter, so Winnie decides it will be fine to let her hair down for one night. When Midas is kidnapped the babysitter fell asleep all hell breaks loose, and every mama is under suspicion. As the investigation gets underway, it seems that every member of the group has some pretty big secrets to hide. Why did Nell delete the video-monitor app from Winnie's phone earlier that night? Who is the token male (literally nicknamed Token) in the mommy group? Readers who can't get enough of suburban suspense along the lines of Liane Moriarty and B. A. Paris will want to give this a try.-