According to an article by doctors Julie M.L.C.L. Dobbeleir, Koenraad Van Landuyt, and Stan J. Monstrey, titled Aesthetic Surgery of the Female Genitalia, and published
in the journal, Seminars in Plastic Surgery (May 2011):
Vaginal tightening surgery has been around since the mid fifties, where gynecologists used to tighten the entrance of a woman's vagina with an extra stitch while repairing vaginal and perineum tears or episiotomies after giving birth. At that time it was notoriously known as the “husband's stitch,” the “husband's knot,” or the “vaginal tuck,” and doctors discreetly referred to this procedure as “improving a woman's well-being.”
The goal of these procedures is to reconstruct (or to narrow) the lower third of the vagina, which includes “the orgasmic platform, internal and external vaginal diameter (introitus) and the perineal body.” The procedure enhances vaginal muscle tone strength and control, and decreases internal and external vaginal diameters. Women choosing to have their vaginas tightened are generally healthy women without true functional disorders. In vaginal tightening procedures, portions of mucosa are excised from the vaginal fornices (via scalpel, needle electrode, or laser) to surgically “tighten” the lower third of the vagina.
The article cites "Green F. From clitoridectomies to ‘designer vaginas’: The medical construction of heteronormative female bodies and sexuality through female genital cutting. Sexualities Evolution and Gender. 2005;7(2):153–187" as a reference.
A 2004 (and 2011 edition of a) book titled, Pregnancy Sucks: What to do when your miracle makes you miserable, by Joanne Kimes and Leslie Young MD, notes:
I do have a secret to let you in on. Some doctors suture your abdominal muscles together again after delivery if you need a C-section. I've also heard that doctors can add an extra stitch if you tear during delivery to tighten yo your vagina (known as a "husband stitch"!). I guess having a baby is as good an excuse as any to have a little work done.
The use of episiotomy during childbirth appears to still be prevalent which could indicate that husband stitches might also still be around. A "birth log" from the '90s (via Snopes) suggests that the practice was perhaps—based on the tone of the article—routinely in use then. Furthermore, the fact that techniques such as vaginal rejuvenation (example) and other solutions such as "vaginal tightening creams" (an astroturfing example) exist, suggest that a corresponding market also exists.