How to Conceive a Boy : Best Ways

How is a baby's sex actually determined?

If you want to know how to conceive a boy, the biology is the right place to start. Every human baby inherits two sex chromosomes — one from each parent. The egg always contributes an X chromosome; the sperm contributes either an X or a Y. If a Y-bearing sperm reaches and fertilizes the egg first, the result is an XY embryo — a boy. If an X-bearing sperm wins that race, the result is XX — a girl. That single moment at fertilization locks in the sex; nothing that happens afterward in the pregnancy changes it.

The global secondary sex ratio sits at roughly 105 male births for every 100 female births, a slight male excess first documented more than three centuries ago. Because males face higher mortality rates throughout life — starting even in the womb — this imbalance evens out by adulthood. But at the moment of conception itself, the split is functionally 50/50: each ejaculation contains roughly equal numbers of X-bearing and Y-bearing sperm, and neither type has a universal biological advantage over the other. That baseline probability is the starting point for every method discussed below, natural or clinical.

What is the Shettles Method for conceiving a boy?

In the 1960s, Columbia University physician Landrum B. Shettles examined hundreds of sperm specimens under a phase-contrast microscope and reported observing two morphologically distinct sperm populations. He classified small, round-headed sperm as Y-bearing (male-producing) and larger, oval-shaped sperm as X-bearing (female-producing). From those observations he concluded that Y-bearing sperm swim faster but are more fragile, while X-bearing sperm swim more slowly but survive longer in acidic conditions.

The practical advice that followed from this theory: couples wanting a boy should have intercourse as close to ovulation as possible — ideally the day of or within 12–24 hours after — because the faster Y-bearing sperm would reach the egg before the longer-lived X-bearing sperm could. Shettles also recommended deep penetration positions to deposit sperm nearer the cervix, where conditions are more alkaline, and an alkaline baking-soda douche prior to intercourse. He claimed an 80% success rate in his 1970 book Your Baby's Sex: Now You Can Choose.

The scientific community has never been able to replicate those results consistently. A 1995 study published in The New England Journal of Medicine — one of the most rigorous examinations of intercourse timing and fetal sex — found no statistically meaningful association between when in the cycle conception occurred and the sex of the baby. A 1991 study in The American Journal of Obstetrics and Gynecology found results opposite to Shettles: fewer male births, not more, when intercourse occurred closest to ovulation. Perhaps most damaging to the method's theoretical foundation, a 2006 paper in the British Medical Journal demonstrated no discernible morphological differences between X-bearing and Y-bearing sperm at all, undermining the classification that the entire method rests on. The Shettles Method has a plausible-sounding theoretical mechanism but has failed to hold up under independent scrutiny.

Does the Whelan Method differ from Shettles?

Elizabeth Whelan, a public health researcher, published her own sex-selection framework in the 1977 book Boy or Girl. Her recommendation for conceiving a boy runs directly counter to Shettles: intercourse four to six days before ovulation, not at ovulation. Whelan's reasoning rested on the idea that biochemical fluctuations in the woman's body during the early part of the cycle create an internal environment that favors Y-bearing sperm, independently of any physical speed or durability difference in the sperm themselves.

The Whelan Method is less widely known than the Shettles Method, and — unsurprisingly, given that the two recommend opposite timing for the same goal — the evidence behind it is no stronger. No peer-reviewed randomized controlled trial has validated Whelan's timing recommendations. The method relies heavily on accurately detecting ovulation via basal body temperature charting, which introduces its own margin of error. The two methods agree on one thing: ovulation tracking matters. But they disagree entirely on what to do with that information, which should give anyone pause about treating either as a reliable guide.

Can diet or supplements influence a baby's sex?

The theory behind dietary approaches to sex selection is that Y-bearing sperm thrive better in an alkaline environment. Foods high in potassium and sodium — bananas, red meat, salty snacks — are thought by proponents to raise the pH of cervical secretions slightly, making conditions more hospitable to Y-bearing sperm. Evening primrose oil is sometimes recommended on the separate premise that it increases the volume of cervical mucus, which in turn is believed to facilitate sperm transport.

A 2008 study in Reproductive BioMedicine Online attracted attention by suggesting that a higher caloric intake and elevated potassium consumption were statistically associated with delivering a boy. The finding was observational — it tracked existing diet and birth outcomes, not an intervention — and the effect sizes were modest. No randomized controlled trial has confirmed that deliberately eating a high-potassium diet before conception reliably shifts the sex ratio. The consensus from reproductive medicine specialists is straightforward: there is currently no clinical evidence that dietary changes can reliably influence whether a conceived embryo will be male or female. You might eat every banana in the grocery store and still conceive a girl, or eat nothing of the sort and have a boy.

The same absence of evidence applies to potassium supplements and to the general "alkaline diet" approach. Altering the body's systemic pH through diet is also physiologically difficult — the kidneys regulate blood pH tightly — so the premise that diet meaningfully changes the pH environment that sperm encounter is itself contested. Healthline's review of the gender-selection diet notes that these approaches should be viewed as unproven folk methods rather than medical guidance.

What do Chinese Gender Prediction Charts actually predict?

The Chinese Gender Prediction Chart — sometimes called the Chinese Lunar Calendar — claims to forecast a baby's sex using two inputs: the mother's lunar age at the time of conception and the lunar month in which conception occurs. The chart is often cited as hundreds of years old, with origins variously attributed to ancient imperial Chinese astronomers or to a Qing Dynasty document.

Its predictive accuracy, when studied scientifically, is roughly 50%. A University of Michigan School of Public Health analysis of more than 2.8 million Swedish births found the chart performed no better than chance. Other published studies report accuracy figures ranging from 45% to 55%, which is statistically indistinguishable from flipping a coin. This outcome is exactly what you would expect from a chart that, biologically speaking, has no mechanism connecting lunar calendars to chromosome inheritance.

The chart's persistent popularity is easy to understand — it's free, it's fun, and half the time it appears to work. But appearing to work 50% of the time is precisely what a random guess would do. For planning purposes, it offers no advantage over chance, and relying on it to time a pregnancy around a preferred sex would be misplaced confidence. Ultrasound at 18–22 weeks of pregnancy, or cell-free fetal DNA testing (NIPT) from around 10 weeks, can identify fetal sex with accuracy above 99% — but only after pregnancy is already established. For more on early pregnancy signs, see our guide to Signs of Pregnancy in the 1st Week.

What is the Ericsson Albumin Method?

The Ericsson Method is a laboratory sperm-separation technique developed by Ronald Ericsson in the 1970s. The procedure works by layering sperm on top of a series of progressively thicker albumin protein solutions in a test tube and allowing them to swim through the gradient under gravity. The idea is that faster-swimming sperm — theorized to be predominantly Y-bearing — will penetrate deeper into the albumin than slower sperm, allowing the lower fraction to be collected and used for intrauterine insemination (IUI).

Ericsson clinics historically reported success rates of approximately 71–76% for male selection. Independent peer-reviewed studies have produced more variable results, with some reporting male birth rates in the 50–75% range when the method is used to select for boys. The technique cannot achieve a clean separation — both X-bearing and Y-bearing sperm end up in every fraction, with only a relative enrichment of one type. This contrasts sharply with methods that work at the embryo stage rather than the sperm stage.

The Ericsson Method is considerably less expensive and less invasive than IVF, which has kept it in use at some clinics. However, its effectiveness has been sufficiently questioned that it is not considered a high-confidence route to sex selection. A couple using this method still faces a meaningful probability of conceiving the opposite sex from the one selected.

Is IVF with Preimplantation Genetic Testing the most reliable option?

Preimplantation Genetic Testing (PGT), used in conjunction with IVF, is the only currently available method that can determine the sex of an embryo before it is transferred to the uterus with very high accuracy. The process works as follows: eggs are retrieved from the woman's ovaries after hormonal stimulation, fertilized in the lab to create embryos, and grown to the blastocyst stage (typically day 5 or 6). At that point, a reproductive embryologist biopsies 5–10 cells from the trophectoderm — the outer layer that will become the placenta — without disturbing the inner cell mass that becomes the fetus itself. Those cells are analyzed using next-generation sequencing or array comparative genomic hybridization, which examines all 24 chromosome types, including the sex chromosomes X and Y. Embryos identified as carrying the desired sex chromosomes can then be selected for transfer.

According to ACOG Committee Opinion No. 799, PGT is an established clinical tool with well-documented utility, though false-positive and false-negative results are possible and prenatal confirmation testing remains advisable. PGT-A (testing for chromosomal aneuploidy) screens all chromosomes simultaneously, making sex identification a byproduct of the broader chromosomal screen. In practice, the sex identification component of PGT is highly reliable — among the most accurate outputs the test produces.

The ethical and legal landscape around non-medical sex selection via PGT varies significantly by country. In the United States, sex selection for family-balancing purposes is legally permitted but is not universally endorsed by medical societies. The ASRM Ethics Committee's 2022 opinion states that while using PGT to prevent serious sex-linked genetic disease is clearly acceptable, using it for non-medical sex selection "can lead to gender bias" and should not be encouraged, though the committee stops short of recommending a legal ban. Several other countries — including Canada, Australia, and the United Kingdom — prohibit non-medical sex selection entirely. Anyone considering this path should verify current regulations in their country and discuss the ethical dimensions with their medical team.

It is also worth noting that IVF itself carries no guarantee of pregnancy. Success rates depend heavily on maternal age, embryo quality, and clinic-specific factors. The financial cost, physical demands of ovarian stimulation, and emotional weight of the process are real considerations that belong in any honest discussion of PGT-based sex selection. Once a pregnancy is confirmed, maintaining intimacy during pregnancy is another aspect couples often find helpful to discuss early.

What should you discuss with your doctor before trying sex selection?

If sex selection is something you are actively considering, the most useful first conversation is with a reproductive endocrinologist (REI) rather than with a general practitioner, because REI specialists have direct clinical experience with PGT, sperm-sorting techniques, and the logistics of IVF. That conversation should cover a few specific areas.

Start with your baseline fertility situation. For couples who are already fertile and simply have a sex preference, the calculus is different than for couples who are already pursuing IVF for infertility reasons — for the latter group, adding PGT-A incurs comparatively little additional disruption. For fertile couples, initiating IVF purely for sex selection means undergoing a significant medical process (hormonal stimulation, egg retrieval, embryo culture) that carries real health considerations and costs, typically ranging from $15,000–$30,000 or more per cycle in the United States before PGT fees.

Ask specifically about your clinic's experience with PGT and their embryo biopsy protocols. The accuracy of the sex identification step depends partly on laboratory technique. Ask also about their policy on untransferred embryos — a common and emotionally significant issue in IVF — and whether they offer genetic counseling as part of the PGT process.

If cost or invasiveness is a concern and you are simply curious about whether timing methods are worth attempting first, your OB-GYN can give you an honest summary of the evidence: that natural methods may marginally shift the odds in one direction, but none has been proven in controlled trials to produce a statistically reliable effect. The biological baseline — roughly equal chances of either sex — remains the most accurate prediction available without clinical intervention.

Frequently Asked Questions

What is the most accurate way to select a baby's sex?

IVF combined with Preimplantation Genetic Testing (PGT) is the only method with documented high accuracy for sex selection. It examines embryos at the chromosomal level before transfer. All natural timing and dietary methods lack peer-reviewed evidence demonstrating reliable effectiveness beyond chance.

Does the Shettles Method really work?

The evidence is inconsistent. Some studies support its timing logic; others found opposite results or no effect at all. A 1995 New England Journal of Medicine study found no association between intercourse timing and fetal sex. The method's theoretical foundation — that X-bearing and Y-bearing sperm have different shapes and swim at different speeds — was challenged by a 2006 British Medical Journal paper finding no morphological differences between the two sperm types.

Is it safe to use a baking soda douche before intercourse?

Vaginal douching of any kind is generally discouraged by OB-GYNs because it disrupts the natural vaginal flora and pH balance, increasing the risk of bacterial vaginosis and other infections. The Shettles Method's recommendation for a baking soda douche predates modern understanding of vaginal microbiome health, and this practice is not endorsed by contemporary reproductive medicine specialists.

Does the Chinese Gender Prediction Chart have any scientific basis?

No. Multiple studies, including an analysis of over 2.8 million births, have found that the chart predicts fetal sex at approximately 50% accuracy — the same as random chance. A baby's sex is determined by which type of sperm fertilizes the egg at conception; lunar calendars have no biological mechanism to influence that event.

Is sex selection legal in the United States?

Yes, non-medical sex selection is legal in the United States, including the use of PGT with IVF for family-balancing purposes. Regulatory status differs widely in other countries — Canada, the UK, and Australia, among others, prohibit non-medical sex selection. Anyone considering sex selection abroad should research the laws of the specific country.

Can I conceive a boy by changing my diet?

No dietary change has been proven in a randomized controlled trial to reliably increase the probability of conceiving a boy. A 2008 observational study suggested a weak statistical association between higher caloric and potassium intake and male births, but the effect was not strong enough to translate into a practical dietary intervention. Reproductive medicine does not recommend dietary sex selection strategies.

What happened to MicroSort?

MicroSort was a flow cytometry-based sperm sorting technology that sorted sperm by DNA content — Y-bearing sperm have slightly less DNA than X-bearing sperm. During FDA clinical trials, it achieved roughly 81.5% male births for the Y-sorted fraction. The FDA did not grant final marketing approval, and as of March 2012, MicroSort is no longer available in the United States. Some clinics abroad continue to offer it.

This article is for general informational purposes only and does not constitute medical advice. If you are considering sex selection methods, consult a reproductive endocrinologist or your OB-GYN for guidance specific to your situation.

If you do learn the sex of your baby through any of these methods, you may also enjoy planning how to share the news — see Ideas on How to Tell Family the Gender of Your Baby. The single most actionable step for anyone seriously exploring sex selection is scheduling a consultation with a board-certified reproductive endocrinologist. That conversation — grounded in your specific fertility history, age, and goals — will reveal which options are medically appropriate, what the realistic success rates look like for your individual situation, and what the financial and physical commitments actually entail. No chart, timing method, or supplement provides a substitute for that conversation. The American Society for Reproductive Medicine's patient resource site is a reliable starting point for finding a qualified specialist and understanding the full range of options.

Olivia Prete

For the past 5 years, she has been sharing her thoughts and experiences through her blog, covering topics ranging from personal development to pop culture. Olivia's writing is honest, relatable, and always thought-provoking.