Meconium is the thick, sticky, greenish-black substance that forms in the intestines of a fetus during pregnancy and is typically the first stool passed by a newborn, usually within the first 24 to 48 hours after birth. It consists of a mixture of intestinal secretions, bile, amniotic fluid, and cells shed from the intestinal lining. The presence of meconium in the amniotic fluid can indicate fetal distress and may lead to complications, such as meconium aspiration syndrome, if inhaled by the baby during delivery.
Only after they are born, they may vomit merconium if they aspirate it before being born. They may also vomit poop if they have intestinal blockage
If you are planning on taking Castor Oil to induce labour it's method of working is to upset the mothers stomach causing diarrhea. This in turn stimulates the uterus to contract and begin labour. However, the castor oil absorbed by the mother and be passed on to the baby causing the baby to release its bowls. This can lead to fetal distress during labour and the aspiration of merconium during the birth process (ie. the substance expelled from the baby's bowels) - fetal distress my result in interventions such as a c-section and aspiration of merconium would lead to breathing problems in the newborn.
ok im not exactly sure how long because the placenta is such a hoarder but id wait like a week before that three month drug screen they give because they don"t test baby merconium for benzos