Human chorionic gonadotropin (hCG) is a hormone made mainly by placental tissue after implantation. It has an alpha part and a beta part. Labs measure the beta part to avoid cross-reaction with other hormones, so clinical reports and our tools refer to beta hCG. Beta hCG is detectable in blood before most urine tests. Levels … Read more
Key points Conception means fertilisation near ovulation, not the day you had sex. The fertile window spans six days and ends on ovulation day. Sperm can survive in the reproductive tract for up to five days, so sex before ovulation can lead to conception later. Implantation happens later again, most often 8–10 days after ovulation. … Read more
When choosing birth control, it’s easy to focus on the method—but how you use it matters just as much. The gap between perfect use (no mistakes) and typical use (real life) can change your odds in a big way. What “perfect” vs “typical” use means Perfect use Taking the pill at the same time daily … Read more
Some contraceptive pairs reduce protection or add risk. If you want to “double up,” choose methods that complement each other—not ones that fight or cancel out. Below are combinations most people should avoid, plus better substitutes. Pairs you shouldn’t mix Don’t mix Why it’s a bad combo Better instead Two external condoms or an external … Read more
Using two methods at the same time can lower pregnancy risk, especially if at least one method protects against user error. The calculator below estimates protection when you combine methods under typical or perfect use. Check your combined protection How the estimate works (plain math) Convert each method’s effectiveness to a failure rate. Example: 95% … Read more
Some pairs of birth control work especially well together. Below are evidence-based combinations that increase pregnancy protection while keeping STI protection in mind. When you want precise numbers for your situation, use our Combined Contraceptive Effectiveness Calculator. How “combined effectiveness” works (in plain English) Each method has a small chance of failure in a given … Read more
Implanon NXT is the etonogestrel contraceptive implant. The product label says to replace it at 3 years. Some studies followed users for longer and found very low pregnancy rates in years four and five. That extended use is off-label in many countries, so decisions should be made with a clinician who knows your situation. What … Read more
Withdrawal can lower pregnancy risk when done perfectly. In real life it fails often. Two findings matter here: pre-ejaculate usually has little or no sperm when there has not been a recent ejaculation, and residual sperm in the urethra seems short-lived and often clears with urination. This is where the informal “5-hour rule” comes from. … Read more
Ovulation “prediction” sounds straightforward—until you look at real cycles. Many popular apps lean on calendar math, but ovulation varies by person and by month. Below is what independent studies and guidelines say, where tracking goes wrong, and practical (evidence-based) ways to time intercourse without overcomplicating your life. What the research actually says Key takeaways from … Read more