You can put that put that vaginal swab away now.

The infant microbiome has been in the news for about a decade, now, after a 2006 study found that babies born via C-section had poorer microbiomes than babies born vaginally. The research was heralded as the key to children’s long-term health. Finally, thought parents and pediatricians, there was an answer to why children born via Caesarean are more prone to obesity, asthma, allergies, eczema, type 1 diabetes and celiac disease. And if there was an answer, there could be a solution, too.

But the past ten years of research has slowly dismantled that theory, culminating in a new study published last week in the journal Nature Medicine that found that while the infant microbiome of babies born vaginally and via C-section differed immediately, they were indistinguishable six weeks after birth.

A microbiome is the collection of microorganisms that live on every internal and external surface of a body and drive a multitude of bodily functions, from immunity to digestion. The 2006 study concluded that the infant microbiome is formed through exposure to the mother’s own microbiome in the birth canal, after nine months of sterility in the womb.

Some women, who underwent a C-section delivery after the 2006 study published, took to requesting that their obstetricians swab their vaginal canals, then swab their babies’ mouth, eyes and skin in an effort to transfer a healthy microbiome, a practice called microbial seeding or bacterial seeding after C-section.

However, “the fetal microbiome is established during gestation,” said Dr. Kjersti Aagaard, a maternal-fetal medicine specialist at Texas Children’s Hospital and a co-author of the latest study, in an interview with STAT.

Which suggests that it’s not the C-section delivery that is skewing children’s chances of good health, but the circumstances surrounding it. C-sections are most common when pregnancies are made risky by mothers’ poor health and habits or for preterm delivery (in the West; in India, C-sections are a controversial norm). These same health issues and habits — obesity or diabetes, for instance; or smoking– have been shown to affect fetal development. In addition, babies born by C-section are more likely to be fed with formula — which a study last year linked to an altered microbiome in infants.

So, while more study is needed to determine not only what affects the development of the infant microbiome and what health implications that has, you can be comfortable that your delivery method won’t have a negative affect on your child (though it may have one on you).

Related: