At the same time, we absorbed parenting differences as if we were conducting an independent study in pediatric anthropology. In Kep, a seaside town in southern Cambodia, we were told that babies’ foreheads should be marked with ash when they leave the house as a measure of protection. In the Laotian village of Nong Khiaw, we were reassured that because our daughter was born in the Year of the Ox, she would become a hard worker and a good wife. In the Vietnamese mountain town of Bac Ha, we were surrounded by Hmong women who said that shamans advise changing newborns’ names if they cry excessively, and they were perplexed when I explained that American mothers typically don’t go to work with their babies strapped to their backs. (They gasped when I told them the going pay rate for New York nannies.)

But the biggest difference between us and those we met had nothing to do with rituals, astrology or superstition. It had to do with motorbikes, which growl along Southeast Asian roads by the million and have become as emblematic of the region as terraced rice paddies and lemon grass. It’s not uncommon to see families of four or five, including children and babies, perched on a single motorbike  without helmets, no less.

Helmetless babies on motorbikes! At home, this could be justification for a child’s removal by state protective services. More than once, when an old woman admonished us for taking our daughter outside in the midday heat, we retorted that at least we weren’t speeding her through knots of traffic in Hanoi on a Honda Metropolitan. Our point simply didn’t compute.

Near the end of our two-month journey, we boarded a small ferry to Quan Lan Island, a sliver of land in Bai Tu Long Bay, east of Hanoi. A squat, rectangular boat with frilly curtains framing the cabin’s windows, its four-hour chug across the bay was so slow and rhythmic as to induce a trance. As we’d become accustomed, Yael was coaxed from our arms by other passengers, and my husband and I both stretched out on wooden benches and dozed.

Every so often, we cracked open our eyes and saw women feeding her peeled litchis and boiled corn, or holding her up to the window to see the sunset’s glow over the crystalline blue water. At one point, we spied her in the arms of the captain, her hand on the wheel of the boat, giggling and gaping at the horizon as we made our way across the sea.