Two millenniums ago, in the foothills of ancient Greece, the physician and philosopher Hippocrates described pregnancy in terms of bread-making. In the thousands of years since, “a bun in the oven” has emerged as a euphemistic image for childbearing. That is, until a study suggested, in 2019, that pregnancy more closely resembles completing an ultramarathon.

This newer metaphor has taken hold on social media, where the hashtags #preconception and #pregnancyprep exhibit women treating pregnancy like “the biggest race of your life, except you don’t know when the race actually starts.” As any serious competitor would, these contenders prepare for months or even years before their gestational events by optimizing their physical conditions and mental health. “Here’s how I’m prepping to get pregnant this year,” one woman says, poised with an iPad in one hand and an Apple Pencil in the other. The caption reveals a sprawling list: “cycle tracking,” “strengthening the pelvic floor, deep core and glutes,” “balanced meals,” “daily meditations” and “financial prep.” It also offers a discount code for her chosen brand of fertility supplements.

This preparatory stage is sometimes called Trimester Zero, riffing off a 2017 book by the sociologist Miranda Waggoner that examines how public health initiatives affect reproductive risk. On social media, however, the concept has evolved into a set of pregnancy “solutions” offered by influencers and online health gurus to the “trying to conceive” (T.T.C.) demographic. The “elite pregnancy prep expert” (and systems engineer) Alexandra Radway, for example, promises that her Baby Ready Body method — a comprehensive “nourish to flourish” plan — supports “engineering healthy, fit pregnancies.” “You wouldn’t summit Kilimanjaro in flip-flops,” she writes in one post. “Pregnancy deserves the same respect.” With the right course of action, the trend implies, you can ward off all undesirable outcomes — not just morning sickness and exhaustion but, as Radway has suggested, even breast cancer.

That kind of mind-set seems to appeal, in particular, to prospective parents feeling trepidation. “I just want to start off by saying that I’m fricking terrified,” Kaylie Stewart shares, in one of seven parts of her ongoing “Prepping for Pregnancy” series. Another post begins with a similar declaration of terror but breaks into a calming montage: a slow walk down a leafy path, a home-cooked breakfast and makeup applied in a fuzzy robe, all set to a mellow tune. The video itself follows a remedial arc, as if its initial anxiety were transmuted, by the structure provided by preparation, into calmer, more productive energy.

Stewart’s content might be soothing to viewers who share her concerns. But TikTok’s For You page can inundate prospective mothers with plenty of other supposed threats. On the podcast “Culture Apothecary,” for example — which pursues “raw, unpasteurized truths” — the conservative influencer Alex Clark parrots unsupported risks of fetal exposure to Tylenol; her “Ultimate Guide to Pre-Conception” identifies dangers like mold, nail polish and food ordered from DoorDash. A large subset of preconception content also zeros in on “nontoxic swaps” for cookware, cleaning supplies, clothing, makeup and air filtration; even the right brand of organic cotton underwear is important, one influencer suggests, “if we want to see our future grandbabies.” (According to this thinking, your fate was decided decades ago by the brand of your grandmother’s knickers.)

In case that pressure wasn’t enough, “prepregnancy glow-up” posts promote plans for becoming not only the healthiest but also the hottest version of yourself before giving birth. “Welcome to a new era,” Gabrielle Meloff announces, by way of transitioning her profile from bridal content to “How I’m Getting Hotter & Healthier Before Pregnancy,” a preconception playlist that complements mood boards envisioning “planning for a pregnancy like a wedding” (featuring images like San Pellegrino in wicker baskets and early 2000s Christy Turlington practicing yoga and towers of rolled-up towels, presumably made from organic cotton).

These fantasies have arisen in a distinctly pronatalist moment, as many continue to push for higher birth rates. Yet material support for having children remains scant. Perhaps women online are simply reading between the lines: It’s on them, and them alone, to create conditions conducive for children. The content that encourages men to partake in prenatal prepping seems only to reinforce that women are exclusively responsible: Husbands aren’t prepping themselves, per se, but being prepped by their wives — who are now tasked with replacing their briefs with boxers and serving up meticulously researched, “fertility boosting” meals from scratch every day, having been permanently scared away from takeout.

After all, a woman online is most celebrated when she treats herself as a never-ending project. Preconception content, then, seems less like practical advice and more like a narrative starting point that allows the story of your life to perform well on social media. Motherhood can be described as tedious, uncertain or isolating — or as the new, empowering chapter for a person devoted to optimization. As one post — a slide show with Hermès baby blankets, bubble baths and freshly cut bouquets — reminds viewers, preparation for motherhood is also preparation “for life.” Its caption could describe any number of contemporary journeys, especially those that live on the internet: “What looks extreme to others is usually just preparation for the future they can’t see yet.”

Kim Hew-Low is an Australian writer living in Brooklyn.