HONG KONG—Giving birth is never easy, but for new Chinese mothers the month following a baby’s arrival is particularly fraught. Immediately after I became pregnant for the first time, I started to hear about zuoyuezi, or “sitting the month.” It’s a period during which new mothers are supposed to stay confined with their babies, and it’s considered crucial, full of strict, sometimes incredible requirements. “Don’t wash your hair.” “Stay away from air conditioning.” “Don’t touch cold water.” “Don’t use cell phones.” These were just some of the more common pieces of advice meted out by a well-meaning army of aunts, older friends, and the cacophony of Chinese social media.

The confinement tradition is so full of elaborate—sometimes contradictory—injunctions and taboos that many new mothers hire live-in professionals to help them navigate the process. An industry that’s both rooted in tradition and tailor-made for modern China has become big business: the yuesao, or “confinement ladies,” who spend a month or two living in the home of a new mother and her baby. Traditionally, a new mom could look to her own mother or mother-in-law to provide vital support during the confinement period. But many young mothers now eschew that arrangement. Having a separate apartment, after all, is now de rigueur among China’s urban newlyweds. And frequent depictions of visceral generational clashes in soap operas, popular novels, and online discussion forums have also instilled a fear of mothers-in-law into younger women.

Mark Ralston—AFP/Getty Images Nurses prepare the VIP ‘Hello Kitty maternity suite’ at the Xi Yue hospital in Shanghai during the auspicious Year of the Pig baby boom, in 2007.

As a result, hiring help during this confusing time has become a popular trend. And given the extremely low birth rate of 0.7 births per 1,000 women in China’s largest cities, partly due to family planning policies, and partly due to the high cost of raising a child, childbirth is a once-in-a-lifetime event for many. That means new mothers, often far more prosperous than the generation before them, are willing to shell out thousands of dollars to make sure they properly navigate the intricacies of the complex, though perhaps not purely scientific, confinement tradition. Although the birth rate is low, yuesao salaries are expected to rise as more families seek out confinement ladies and China further relaxes family planning restrictions to allow more babies.

Historically, the month has been sacrosanct in Chinese culture. Overexertion and blood loss during birth weakens a woman’s chi, the theory goes, while exercising, exposure to anything cold, or negative emotions during the recuperation period can cause long-term damage to the new mother’s energy flow. The list of potentially offending activities can be long and confusing. Some traditions forbid leaving the house altogether. Others recommend drinking liquids from evaporated rice wine instead of water for an entire month. Still others advise against adding salt and soy sauce to any food. Even articles that purport to debunk confinement myths often give their own bewildering suggestions—it’s an old wives’ tale that eating raw fruits after birth would harm one’s pancreas, according to one article on Mama.cn, a site popular with new mothers. But the article also insists new mothers dunk fruits in hot water first to prevent “blood congestion” in their stomachs and intestines.

Bulwarks of cultural transmission, such as my mother, attribute anything from lethargy, premature aging, gout, arthritis, and back pain in old age to an earlier failure to observe confinement practices correctly. “You’ll regret not doing confinement properly when you are 50,” she admonished in her gravest tone, when I voiced some objection about the dubious benefits of confinement practices. When even my mother, trained as a chemical engineer at one of China’s top universities and not easily given to superstitions, repeats these same dubious refrains, it becomes easier to understand how millions of Chinese matrons do the same to their own daughters and daughters-in-law. While I think of myself as a modern, rational woman, I am also Chinese—who am I to flout the rules that generations of my foremothers have chosen to follow?

The day after my baby girl and I came home from the hospital, the woman I’d hired as my own confinement lady promptly turned up. We called her Sister Yun. A pudgy woman in her 50s, Yun had moved to Hong Kong from mainland China almost three decades ago. “We didn’t have anything to eat when I was growing up,” she would mumble whenever I asked her to throw away the last bits of leftovers. Since her husband and two grown sons had no steady jobs, Yun’s skills as a yuesao were what kept her family afloat. “Two sons, two wedding banquets to pay for,” bemoaned Yun. “Girls are better.” But as soon as she found out that I was expecting a girl, she betrayed her deep-seated preference for sons, telling me, “It’s okay. You are young and can still try for a boy.”

Yun would arrive every morning with raw fish, chicken, tofu puffs, vegetables, red dates, ginger, and other groceries to prepare special confinement meals for me. To her chagrin, I rejected Chinese medicinal soups and even pork knuckles stewed in vinegar, a local Cantonese delicacy considered essential for postnatal recovery. She chalked it up to me having lived in the United States for too long and let it slide. But when she found out that I had taken a shower and washed my hair a week after giving birth, she could no longer keep silent. “Aiya, how could you!” she huffed. “Your pores open up after you shower and the cold air goes straight to your bones!” I sheepishly admitted that the dry shampoo was not cutting it for me anymore. She gave in a little. “I’ll boil some ginger water for you,” she conceded. “Sponge baths only.”

The logic behind the confinement practices is more sociological than scientific.

The logic behind the confinement practices is more sociological than scientific. One of the more plausible explanations for confinement rules can be found on Zhihu, an online question-and-answer forum similar to U.S. site Quora. One Zhihu user conjectured that the traditions had developed when China was largely an agrarian society with high mortality rates among postnatal women and infants. As recently as the early 1980s, wrote the user, much of the rural population lived in houses built with mud and thatch. Many of the confinement rules are crude proxies for better hygiene—for example, evaporating rice wine was an attempt to purify water. Over the centuries, the user surmised, those rules of thumb had hardened into norms that were passed down from one generation to the next as inviolable cultural practices.

Confinement tradition is also well established in Taiwan, Singapore, and among overseas Chinese elsewhere. Just as the practice may seem exotic or quirky to outsiders, the lack of the same elsewhere serves as a subject of constant wonderment to Chinese people. “Shocking! Why don’t new mothers in foreign countries practice confinement?” is an oft-seen headline on China’s mom-centric websites. One article in Hong Kong newspaper Wen Wei Po titled “Why Princess Kate Does Not Practice Confinement” theorized, with no scientific evidence whatsoever, that foreign women’s high-calorie and high-protein diet is the reason for their stronger constitutions; but it warned darkly, again without sources, that foreign women contract “female diseases” more easily later in life because of poor recuperation after birth.

Yuesao are usually middle-aged women from the countryside with little formal training, and their success has encountered a bit of snobbery. “Yuesao salaries higher than [for those] with medical degrees,” proclaimed one December 2013 article in the state-run Beijing Evening News, which also noted that some confinement ladies were booked up to two years in advance.

In Hong Kong, where I live, confinement ladies command about $2,000 a month, 30 percent more than what new college graduates make on average. According to the Paper, a news site based in Shanghai, the average going rate for an experienced confinement lady there reached $1,600 per month in December 2014, or about twice the average monthly salary in China’s largest city. Confinement ladies with good recommendations can easily take home more than $2,000 a month in Shanghai. That’s more than Chinese President Xi Jinping makes.

Ironically, the seemingly equalizing trend is driven mostly by income inequality. In one sign of the times, the wealthiest echelon of women can now forego yuesao and spend their confinement month in maternity hotels staffed with nannies, nurses, and nutritionists. Out of over 100 maternity hotels in Shanghai listed on Dianping.com, a rating website for local businesses, average monthly prices ranged from $4,500 a month to more than $19,000. One center has photos featuring yoga classes, afternoon teas with expensive Chinese delicacies, and a “Presidential Suite” costing more than $30,000 a month.

In the end, my confinement was an exercise in compromise. I showered every third day, sometimes dousing myself with ginger water, sometimes not. I slipped out for a few short walks with my husband, weathering disapproving glances from Sister Yun. I stayed away from ice cream, but indulged in some apple slices without dunking them in hot water. Exactly one month after I had my baby, I celebrated liberation from confinement with a large milkshake. I remain unconvinced those sacrifices were necessary, but it was nice to have Yun around. She did all the cooking, gave me breastfeeding tips, bathed my child, and allowed me to catch up on much-needed sleep. I had more time to bond with my baby and a bit more confidence to care for her. Missing a few showers—even parting with a couple thousand dollars—seemed worth it.