Hypomineralisation is a condition that affects the outer layer (enamel) of your child's teeth. It occurs due to a disturbance during tooth development, either during pregnancy or in the first two years of life. This could be linked to any number of factors, including low birth weight, metabolic disorders, malnutrition, respiratory problems, antibiotics or high fevers. We know that diet or hygiene aren't to blame, so that can be ruled out. Molar hypomineralisation occurs while teeth are still forming in the jaw.