Smoking in pregnancy causes all except :

Smoking Carbon monoxide and nicotine are responsible for fetal adverse effects.There is an increase in miscarriage,abruptio placenta,preterm premature rupture of membranes,preterm labour,and intrauterine growth restriction.There is an increased risk of sudden infant death postpaum.Both active and passive smoking are implicated TEXTBOOK OF OBSTETRICS,SHEILA BALAKRISHNAN,pg no:574,2nd edition