Milk this for all it’s worth.

While there’s strong consensus among medical experts that “breast is best” for babies, the ideal duration of breastfeeding — six months? A year? Until the kid is way too old and it becomes a little creepy? — has always been murkier.

New research out of China might offer better-informed advice for when to wean. 

Analyzing data collected for a national family survey, the researchers found that longer breastfeeding periods gave children a leg up at school, especially for those with lower socioeconomic status.

Kids in China aged 10 to 15 were given cognitive assessments to test their math and language skills. Among the lower socioeconomic cohort, those who had been breastfed for longer as babies performed better on the tests.

For Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Northwell Cohen Children’s Medical Center, these results not only confirm pre-existing knowledge that breastfeeding tends to have “favorable longer-term outcomes,” but they highlight something that’s often overlooked or misunderstood.

“It’s not just about whether breastfeeding is better than not breastfeeding, but rather that breastfeeding for a longer period of time is important,” he told The Post.

While other research has produced similar results, the study authors looked specifically at the benefits of breastfeeding for longer than six months. 

The American Academy of Pediatrics encourages women to breastfeed for more than a year, but only 35% of women in the US do.

“I think that in the United States, we probably should be doing much better in terms of women breastfeeding for a longer period of time,” said Adesman, who was not involved in the new study.

Typical obstacles to breastfeeding include physical troubles like sore nipples and low milk supply, as well as barriers such as lack of maternity leave and limited support from family members or employers.

This study’s focus on socioeconomics offered a unique dynamic, Adesman noted.

There’s some concern that breastfeeding studies conducted in “more advanced, wealthier countries” — where “breastfeeding is more common in upper income households and less common in lower income households” — might have slightly skewed results because of other lifestyle factors that could be boosting health outcomes for babies. 

But in China, “it’s actually the reverse,” he said. 

Breastfeeding is more common among families with lower socioeconomic status, Adesman said. And in those populations, the advantages of breastfeeding “are evident.”

As for why longer breastfeeding may have an impact on intellect, attention and behavior, Adesman chalks it up to the nutritional and social benefits, though we don’t totally know for sure.

Nutritionally, experts agree that it’s impossible to beat human milk. Dr. Julie Ware, president of the Academy of Breastfeeding Medicine, calls it “personalized medicine” — “perfectly matched for the infant’s needs.” 

And the benefits of breast milk go beyond nursing the next Einstein. 

Ware recently told The Post that human milk “not only provides optimal nutrition, but it provides immune protection for the human infant.”

Without the “protection of human milk,” she said, babies face heightened risk of “a multitude of infectious diseases,” plus complications down the line, like diabetes, asthma and even childhood cancers.

Breastfeeding isn’t just good for babies, either. It’s also generally good for parents. 

In the immediate, moms who don’t nurse might experience severe breast pain and engorgement, mastitis and psychological distress.

And over time? “There are some health benefits for women who breastfeed,” Adesman said, including lower risks of breast and ovarian cancers and heart disease. 

He acknowledged that for some new moms, it may be too difficult to breastfeed. 

But “the longer the women choose to breastfeed or are able to breastfeed, the greater the benefits,” he said.