A baby’s sex at birth might not be the equal coin toss that we’ve always believed it to be. A new study published by the Harvard TH Chan School of Public Health, titled, “Is sex at birth a biological coin toss? Insights from a longitudinal and GWAS analysis” challenges this long-held assumption.

The study was published on July 18 in the journal Science Advances, and it found that several factors, including a mother's age, genetics, and the sex of older siblings—may influence whether she’s more likely to have a boy or a girl.

Patterns Behind the Birth of Boys and Girls: How Was The Study Conducted?

The research looked at more than 146,000 pregnancies involving over 58,000 U.S. nurses from the NIH-funded Nurses’ Health Study, covering the years 1956 to 2015. What they found was eye-opening: families with three or more children were more likely to have either all boys or all girls than if the sex of a child was purely random.

“If you’ve had two or three girls and you’re trying for a boy, your odds aren’t 50-50 anymore,” explained Jorge Chavarro, professor of nutrition and epidemiology and the study’s senior author, in a quote to The Washington Post. “You’re more likely to have another girl.”

Also Read: It Might Not Be Diabetes; It Could Be This Common Pill Causing Heart Disease: Study

The Role of Maternal Age and Genetics

One of the biggest surprises was the link between maternal age and the likelihood of giving birth to all children of the same sex. Women who started having children after age 28 had a slightly higher chance of giving birth to only boys or only girls.

Researchers believe this could be due to biological changes that come with age, such as shifts in hormone levels or physical conditions that may affect which sperm survive and fertilize the egg.

Additionally, the study identified two specific genes that appear to be linked with the likelihood of having children of only one sex. While scientists don’t yet know how these genes affect birth sex, their discovery opens the door for further research.

Chavarro noted that future studies should explore whether lifestyle choices, diet, or even exposure to certain environmental chemicals might also play a role.

Are Families Subconsciously Seeking “Gender Balance”?

The study also touches on social patterns. In families with two children, there was a higher chance of one boy and one girl. Researchers believe this may be because couples tend to stop having children once they have one of each sex, possibly due to a preference for a “balanced” family.

This idea is supported by another paper published in the Journal of Behavioral and Experimental Economics, which jokingly refers to parents who have three boys or three girls as those who “lose the birth lottery.”

When Expectations Don’t Match Reality

The findings also bring up the topic of “gender disappointment”, a real emotional experience for some parents when the sex of their baby isn’t what they hoped for.

A 2023 paper in the BJPsych Bulletin found that in many Western families, this disappointment often stems from a desire to experience raising both sons and daughters.

In everyday life, these expectations can be seen in subtle remarks like “Four boys? Poor you,” or “Still trying for a girl?”, comments that reflect how deeply society views gender roles and balance, reports CBC.

What It Means for Expecting Parents

While the science behind birth sex is clearly more complex than a simple 50-50 chance, experts agree it’s not something to stress over. Rather, it’s a reminder that biology, age, genes, and personal choices all come together in ways we’re only beginning to understand.

One of the biggest concerns that comes forth with excessive internet use is misinformation. While people are constantly warned about the same, the major problem arises when teens start relying on this data for their health. This is not a ‘one off’ instance where some teens follow this pattern, but it is an on-going issue. What we must do is find the reason why, why do teens find it easier to rely on unverified medical information, and how many teens do so.

What many people will be surprised to know is the sheer amount of kids who are looking for health information online. A new study done by health and well-being app Luna shows that many teen girls are looking for health advice online, using Google or apps like TikTok, instead of talking to a doctor.

Teens Turn to the Internet for Health Answers

A recent survey of nearly 2,500 young people by a teen health app found that almost a third of teen girls (31%) are searching online for health information. In contrast, only 27% of them talk to their parents or guardians. This trend is concerning, leading experts to encourage parents to create an open and non-judgmental environment at home so their children feel comfortable discussing health concerns with them and with doctors.

What Do Teens Look For?

However, this is not the only data available on the matter. According to the 2014 Young Adult Library Services Association journal, teens often turn to the internet for health information due to its accessibility, affordability, and anonymity, even though they often prefer asking people directly.

They seek information on a wide range of topics, from illnesses and accidents to sexual health and mental health. Sexual health and drugs are particularly popular topics. Often, teens look for information when they face a problem (e.g., a personal health concern) rather than for proactive health maintenance (e.g., nutrition).

Why Teens Avoid Talking to Adults

One of the main reasons teens turn to social media or the internet for health advice is embarrassment or shame, which prevents them from seeing a doctor. Another significant factor is that they don't feel comfortable talking to their parents; 19% of teens in the study said they avoid the doctor because they don't want their parent or caregiver to know about their health issues.

The 2014 review also mentioned how girls are twice as likely to seek health information online, though they may have less access to technology and fewer tech skills than boys. Girls are more likely to seek information for family or friends and are more concerned about violence and victimization related to sexuality. Male peer norms and perceptions of masculinity can also lead boys to deny health problems and avoid seeking online information.

Encouraging Open Conversations at Home

Experts suggest that for this pattern to change, parents might need to actively remind their pre-teens and teens that they are always available to discuss anything. While it can be challenging to get a young person to open up, experts emphasize that parents don't need to have all the answers. Instead, it's about being a trusted presence who listens without reacting harshly or jumping to conclusions.

The study also highlighted that regular check-ins can help build trust over time, signaling to teens that it's okay to talk about sensitive or confusing topics.

The Dangers of Online Health Advice

The co-founder of the teen health app emphasized that how teen girls feel about discussing their health needs to change. It's troubling to see so many resorting to apps like TikTok or Google for answers instead of speaking with a doctor or their parents.

While some helpful advice can be found online, there's also a vast amount of incorrect information that could cause more harm than good. This highlights the urgent need for safe and reliable spaces where teens can learn about their health and well-being.

The State Task Force (STF) for Improving Sex Ratio in Haryana announced that couples with one or two living female children seeking another child through IVF must get a prior permission from a District Appropriate Authority. The decision came in the backdrop of state's sex ratio, which has gone up to 904 girls for every 1,000 boys till July 5 this year, from 903 last year.

But, does curtailing IVF right really make a difference? On the World IVF Day, Health and Me spoke to Dr Archana Dhawan Bajaj, a gynaecologist and IVF Expert at Nurture to know what she thinks about this recent decision.

Can You Know Your Child's Sex In IVF?

Dr Bajaj points out that when a couple conceives through IVF, a preimplantation genetic diagnostic (PGD) test is performed to screen the embryo for genetic abnormalities. However, it also determines its sex. While declaring a child's sex in India is illegal, she notes that, "activists and authorities claim that it is carried out discreetly in IVF clinics across the country."

She also explains that despite the law banning sex determination at birth, IVF doctors in various parts of the nation receive inquiries every month about PGD for sex selection, with 90% of them wanting a son. Dr Bajaj says, "They literally beg: 'We won't tell anyone, so please do it'."

Since sex determination is illegal in India, some wealthy couples avoid the laws entirely, by "opting for IVF treatment in countries where sex selection is legal, such as the UAE and Thailand", points out the doctor.

The question arise, if IVF also does not let couples in India predetermine the child's sex, then does curtailing their right to go for an IVF baby then make any difference? "Policies such as that of Haryana, which obligates couples who have children of the gender that they do not want, such as daughters, to apply to have IVF, are supposed to negate this trend among sex selection," explains Dr Bajaj.

While it’s understandable why such regulations have been introduced, this approach risks unfairly penalizing families and infringing on reproductive rights. "In India, laws prohibit sex selection in the context of IVF and pre-implantation genetic diagnosis (PGD). However, many doctors report that requests for sex selection, primarily for male children, remain common in clinical practice," she says.

So, What Should The Approach Be Like?

"Instead of placing restrictions on patients, the focus should shift towards tighter regulation of fertility clinics and stronger legal action against violations," points out the doctor. She says that long-term solutions lie in gender sensitization and public education, which address the root of gender bias rather than simply punishing families for their reproductive choices.

Imposing limitations based on the number of children or enforcing bans without broader reform can be counterproductive. "Such actions may breed fear and stigma, without actually changing the societal mindset. Real progress requires a balance—upholding ethical medical practices while respecting reproductive autonomy," she says.

The views expressed in this article are those of the doctor and do not necessarily reflect the views of Health and Me.

Pregnancy occurs when a sperm fertilizes an egg released during ovulation. The fertilized egg travels down the fallopian tube and attaches to the lining of the uterus, where it begins to grow. Ovulation typically occurs about 14 days before the start of the next menstrual period, making the days just before and during ovulation the most fertile window.

Experts suggest that the best time to conceive is during this fertile window, often spanning five to six days in the middle of the menstrual cycle. Factors such as age, lifestyle, medical history, and reproductive health play an important role in conception.

Once pregnancy is confirmed, ongoing medical care and regular monitoring are essential to ensure both maternal and fetal health. However, several complications may arise during pregnancy, even in otherwise healthy individuals.

Below are three common pregnancy-related complications and what to know about them.

Gestational Diabetes: Temporary but Significant Condition

What it is:

Gestational diabetes is a condition in which blood sugar levels become elevated during pregnancy. It is typically diagnosed between the 24th and 28th week of gestation and results from hormonal changes that impair the body’s ability to use insulin effectively.

Risks:

If left unmanaged, gestational diabetes can lead to several complications. These include high blood pressure during pregnancy, delivering a larger-than-average baby (macrosomia), and an increased likelihood of cesarean delivery. The baby may also face short-term issues like low blood sugar after birth and long-term risks such as obesity and type 2 diabetes.

Symptoms:

Often asymptomatic, but some individuals may notice increased thirst, frequent urination, fatigue, or nausea.

Management:

Management typically includes dietary changes, moderate physical activity, and frequent monitoring of blood glucose levels. In certain cases, insulin therapy may be required to maintain optimal blood sugar levels. Timely diagnosis and control are critical to preventing complications.

Preeclampsia: A Serious Hypertensive Disorder

What it is:

Preeclampsia is characterized by high blood pressure and signs of organ dysfunction, most commonly affecting the liver and kidneys. It generally occurs after 20 weeks of pregnancy but can also emerge in the postpartum period.

Risks:

If not treated, preeclampsia can progress to eclampsia, a condition marked by seizures. It also increases the risk of stroke, organ damage, placental abruption, and can result in preterm birth or restricted fetal growth.

Symptoms:

Signs include high blood pressure, protein in the urine, persistent headaches, visual disturbances, pain in the upper abdomen, nausea, and swelling—especially in the face and hands.

Management:

Treatment depends on the severity and the stage of pregnancy. For mild cases, blood pressure monitoring and medication may be sufficient. In more severe scenarios, early delivery may be necessary to protect the health of both mother and baby. Regular prenatal care is key for early detection.

Placenta Previa: A Structural Concern in Pregnancy

What it is:

Placenta previa occurs when the placenta partially or fully covers the cervix, which can obstruct the baby’s exit path during labor.

Risks:

This condition can lead to severe bleeding during pregnancy and delivery, potentially endangering both maternal and fetal health. It also increases the chances of preterm delivery and often requires a cesarean section.

Symptoms:

The primary symptom is painless, bright red vaginal bleeding in the second or third trimester. Some individuals may also experience mild cramps or contractions.

Management:

Management strategies depend on the extent of placental coverage and gestational age. These may include pelvic rest, reduced physical activity, hospitalization, or planned early delivery via cesarean section.

Importance of Early Monitoring

Early diagnosis and appropriate intervention can significantly reduce the risks associated with these complications. Routine prenatal checkups, diagnostic tests, and being alert to changes in the body help ensure timely management and improve outcomes for both the pregnant individual and the baby.