Spanish researchers studying the detection of substances in breast milk have recommended that breastfeeding mom totally avoid drug abuse so as not to pass drugs to newborn.

The researchers from the Paediatrics Department at the Hospital del Mar in Barcelona also recommended that pregnant and breastfeeding mothers avoid smoking, drinking coffee and drinking alcohol to avoid passing nicotine, caffeine and alcohol to their babies.

Based on their study, the researchers found that breast milk of smoking mothers contains between 2 and 240 nanograms of nicotine per milliliter. This means their babies also receive 0.3 to 36 micrograms/kg/day causing them to suffer more from colic and making them more prone to respiratory infections.

The study recommended that breastfeeding mothers reduce consumption of coffee, tea, cola drinks and medicines with caffeine to three cups per day.

Breastfeeding mothers who take marijuana, cocaine and other drugs can cause sedation, lethargy, weakness and poor feeding habits in breastfeeding babies, warned the study appearing in this month's issue of the journal Analytical and Bioanalytical Chemistry.

Alcohol in breast milk can harm the infant's motor development, change their sleep patterns, reduce the amount they eat, and increase the risk of hypoglycaemia. To minimize such risks, the researchers recommended feeding the baby before taking alcohol.

Meanwhile, babies exposed to marijuana in breast milk or smoke from their mothers can get sedated, lethargic and weak. Mothers who take marijuana are advised to do so several hours before feeding their baby.

Cocaine-using mothers should totally avoid the drug as this had already caused a two-week-old baby boy to suffer irritability, trembling, dilated pupils, tachycardia and high blood pressure after feeding, the study said.