Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. Breastfeeding can lead to rise in the hormone Oxytocin levels to some extent and sometimes that can lead to premature uterine contractions. So better to be careful while breast feeding during the pregnancy. If your first baby really needs your milk you may continue for one or two months and try for weaning and supplementing with other foods. While continuing the breastfeeding you may have features like sore nipples, excessive fatigue etc. By taking additional calories than prepregnacy you can avoid some amount of fatigue. You have to continue with regular antenatal check ups with your gynecologist and ultrasound examinations to monitor the growth of the intrauterine baby. Hope I have answered your query. Let me know if I can assist you further.