Breasts – or mammary glands – are a defining feature of animals which give birth to, and feed, live young, but humans are unique in identifying breasts as sexual. French king Louis XV is rumoured to have declared, “And her breasts? That’s the first thing one looks at in a woman.” A 2011 study published in Archives of Sexual Behaviour , based on research conducted at the Victoria University of Wellington in New Zealand, lends credence to the king’s observation, saying that breasts are often the first thing men look at when they see a woman, and for a longer time than other body parts. No two pairs of female breasts are alike, nor are the two in one pair the same. No woman has a perfectly symmetrical bust: the breasts may vary in size, one might sit slightly higher, or be more round or pert than the other. The differences are perfectly normal. Breasts are composed almost entirely of fat – they contain no muscle – and are built of a series of lobes arranged like the petals of a flower. Within each lobe are smaller parts known as lobules, and the whole arrangement is linked by milk-producing ducts which lead to the nipple in the centre of the areola, the brown bit in the middle from which a baby suckles. Women are the only female mammals whose breasts begin to grow at puberty and remain enlarged, independent of pregnancy, and whose breasts retain a fullness after pregnancy and nursing. Humans are also the only species to stimulate female breasts during sex. Why? Some biologists suggest breast fullness signals good health and so indicates that a female makes a good mate. When a human female is sexually aroused, her breast volume increases and the nipples stand erect. Studies show that nipple stimulation activates the same areas in a woman’s brain as genital stimulation. This arousal triggers the release of the neurochemical oxytocin, often nicknamed the “love drug” , which focuses a woman’s attention on her sexual partner and heightens desire. When a woman’s nipples are stimulated by her baby during breastfeeding , oxytocin floods her brain again, but this time it helps her focus on her baby. The sexual response to her partner fades and the nurturing one kicks in as her breasts morph from sensual to sustaining. As a baby nurses (and the areolas give off a scent that only babies can detect), it prompts nerves in the nipple to nudge the release of not just oxytocin, which helps to “let down” the milk, but also prolactin, which signals the production of that milk. Oxytocin helps to widen ducts making flow easier. Sometimes a woman’s “let down” is so strong it the early days of breastfeeding that just thinking about her baby will cause a flood of milk. The breast doesn’t just know when and how to produce milk for a nursing baby, but knows precisely how much. It works on a supply and demand system, meaning the more milk the baby requests, the more the body will make. Hong Kong mother fights to normalise breastfeeding But not all women want to, or are able to, breastfeed. Sometimes breastfeeding is hindered by previous breast augmentation. “Breast augmentation has the potential to affect the nerves and ducts within the breast, thus impacting lactation,” says Dr Stephanie Lau, a Hong Kong specialist in general surgery with a particular interest in breast surgery. According to the International Society of Aesthetic Plastic Surgery, breast augmentation is the most common cosmetic surgical procedure performed worldwide. In 2018, more than 1.84 million women globally underwent breast augmentation. In the Asia-Pacific region, Lau says, China dominated the breast implant market in 2019, accounting for over 30 per cent, followed by Japan. The value of the market for breast implants in Asia-Pacific is estimated to reach US$329.5 by the end of 2027. What is driving demand? Generally speaking, Lau says, “women who choose to have breast augmentation are educated about the procedure and confident about their decision. They want to boost self-esteem and feel younger and more feminine. Some patients opt for it because they have disproportionately small breasts, obviously asymmetrical breasts, or their breasts changed shape following pregnancy or recent weight loss.” The first documented breast augmentation was performed by surgeon Vincenz Czerny in Germany in 1895 on a 41-year-old singer who had a tumour removed from one breast. To address the resultant lopsidedness, Czerny removed a similarly sized benign fatty tumour from her back and inserted it into the space in her left breast. From there, doctors imitated Czerny’s procedure by implanting at random, and with apparently little thought for patients’ welfare, a series of implants – from kerosene and glass balls to wool. Many botched procedures and numerous deaths resulted. Breast implants are foreign to the body … It is not uncommon for patients to require additional surgeries for implant revision or removal Dr Stephanie Lau, Hong Kong specialist in general surgery During World War II, Japanese sex workers injected industrial-grade silicone into their chests (mostly with less-than-happy ultimate outcomes) to lure American servicemen whose tastes in women were drawn from the buxom likes of American actresses Marilyn Monroe and Jayne Mansfield. A Texan divorcee and mother of six, Timmie Jean Lindsey, became the first woman to receive silicone implants – in 1962. She had visited the doctors to get a tattoo removed from her chest and asked about having her ears pinned back. Her surgeons were looking for an implant guinea pig, and she was willing. Though implants and the attendant surgery are safer now, breast augmentation is not without risk . “Breast implants are foreign to the body – there are a number of associated complications,” Lau says, including hardening around the implant (capsular contracture) leading to deformity and pain, leakage, rupture, infection, erosion, and exposure. “It is not uncommon for patients to require additional surgeries for implant revision or removal,” she adds. Dr Polly Cheung, founder of the Hong Kong Breast Cancer Foundation, says that very occasionally, “breast augmentation may cause ALCL, a rare cancer type”. Sometimes, breast augmentation is performed after breast cancer, as it was in Czerny’s first patient, to redress the balance and restore a woman’s profile post-mastectomy. Breast cancer has become the most common cancer affecting women in Hong Kong, “and the third most lethal”, Cheung says. Local numbers have increased almost fourfold since 1994. One in 15 women in Hong Kong develops breast cancer during their lifetime, Cheung adds. Risk factors associated with breast cancer, Lau says, can be divided into non-modifiable and modifiable. Non-modifiable include those you can’t do much about: age, genetic mutations (the BRCA1/2 genes) and a history, or family history, of cancer. Modifiable risks – the ones we can do something about – are usually lifestyle-related and include physical inactivity, too much alcohol, smoking and a poor diet. Having less than three hours of exercise a week, being overweight and high stress levels all increase the risk of breast cancer, Cheung says. Lesser known is that women who do not breastfeed their newborns are also at risk, because women who breastfeed have fewer menstrual cycles, and so less exposure to oestrogen, which is the catalyst in some breast cancers. Additionally, breastfeeding may make breast cells resistant to the mutations associated with cancer. Big, small, natural or not, the human female breast, whether playing seductress or sustaining the life of a newborn, is a clever body part – definitely as much brain as beauty.