Probably not. It's great to take your vitamins, but they're more for you than for baby. At 10 months, your little one is likely to be exposed to lots of germs and viruses that she's never encountered before. She's also probably taking less breast milk and more solids, and is less protected by the passive immunity that comes from your milk. Your milk is still just as nutritious as before you stopped the prenatals; it's simply time for baby to start building her own immunities. Colds are no fun, but they happen to everyone. Rest assured that by breastfeeding you've given baby her best weapons to fight infections effectively.