Avoid certain foods (maybe spoiler)
When Kate and Justin take the baby to the hospital, she is told that she can continue breastfeeding only if she cuts out certain foods the baby is allergic to. Kate asks what foods, looks are exchanged between doctor and husband, but we don't hear the doctor's reply.
This looked a plot strand being set up that the director may have decided not to follow up on, in which case the doctor's answer didn't matter.
But there was a bit of emphasis on lemons (the lemonade, the water jug in the restaurant), and I'd love to know if there was initially intended to be significance to the food angle that would cast suspicion on 'the ones below' that was abandoned.