I m concerned for baby head growth. she is 18 days old.born with 37 cm head circumference today 40 cm.is that normal.

Too fast: If your measurements are accurate then a 3 cm increase in 18 days is too fast. Normal head growth in the first few months for a full term baby is approximately 1cm every 2 weeks. Getting an accurate head circumference can be difficult. I would recommend having your pediatrician check the head circumference to confirm the measurement and decide if further work up is indicated.

Large head: 40 cm at 18 days is large. IF there is no bulging of the fontanelle, the difference may be due to molding durign the delivery. Was this a large baby? Is there a family history of large heads. If there is any concern, speak to your pediatrician andi f necessary have an ultrasound done.