At nearly $800 a pop, the Artipoppe “Zeitgeist” carrier has seemingly surpassed a coveted Hermes handbag as the must-have accessory — at least, that’s how it looked to Libby Newman.

For babies who suffer from reflux or spit up frequently, the upright position or koala hold is often the most comfortable breastfeeding position. Apart from preventing spit up in babies, this is also ...