For many people, "trying to conceive" (TTC) starts with a mix of excitement and uncertainty. The good news: for most couples under 35 who have regular cycles, conception happens within 12 months of trying. But that doesn't mean there's nothing you can do to improve your odds and reduce the guesswork. Here's what the evidence shows.
Understanding the Fertile Window
Conception is only possible around the time of ovulation — understanding your cycle phases makes pinpointing this window much easier. After ovulation, the egg survives for just 12–24 hours. Sperm, however, can survive in the fallopian tubes for up to 5 days — which creates a fertile window of approximately 5–6 days per cycle: the 4–5 days leading up to ovulation, the day of ovulation itself, and possibly the day after.
The highest pregnancy rates are achieved with intercourse in the 2 days leading up to ovulation — because this is when sperm are present and ready when the egg arrives.
How to Track Your Fertile Window
There are three main methods — all central to fertility awareness methods — and using them together (the "symptothermal method") gives the clearest picture:
Basal Body Temperature (BBT)
BBT is your lowest resting temperature, taken first thing in the morning before getting out of bed. After ovulation, progesterone causes a rise of 0.2–0.5°C (0.4–1°F) that persists until your next period. This temperature shift confirms ovulation occurred — making it retrospective rather than predictive.
To use BBT: take your temperature at the same time each morning using a dedicated BBT thermometer (accurate to 0.1°), before any movement or activity. Chart it daily. After 2–3 cycles you'll see your personal pattern clearly.
LH (Ovulation Predictor) Strips
Ovulation predictor kits (OPKs) detect the surge of luteinising hormone (LH) that triggers ovulation 24–36 hours later. They're the most reliable way to predict (rather than confirm) ovulation.
- Start testing a few days before your expected ovulation window
- Test at the same time each day (afternoon is generally recommended)
- A "positive" result (test line as dark or darker than control line) means ovulation is likely within 24–36 hours
- People with PCOS may have elevated LH throughout their cycle, causing false positives
Cervical Mucus Observation
Cervical mucus changes are driven by oestrogen and provide a real-time window into your fertility status. As ovulation approaches, cervical mucus transitions from dry or sticky → creamy/white → clear, slippery, and stretchy (like raw egg white). "Egg white" cervical mucus is your best natural indicator of peak fertility and can be observed daily.
Lifestyle Factors That Impact Fertility
A number of lifestyle factors have solid evidence behind them when it comes to optimising fertility:
Diet and Nutrition
A balanced, nutrient-rich diet supports hormonal health. Evidence favours:
- Folate/folic acid: 400–800 mcg daily, ideally started 3 months before trying to conceive. Critical for neural tube development in early pregnancy.
- Anti-inflammatory foods: Oily fish, olive oil, nuts, seeds, leafy greens, and berries are associated with better fertility outcomes.
- Reducing ultra-processed foods: High sugar intake can worsen insulin resistance, which disrupts ovulation.
- Iron-rich foods: Non-haem iron (from plants) has been associated with lower ovulatory infertility risk in some studies.
- Vitamin D: Deficiency is common and associated with reduced fertility. Consider getting levels tested and supplementing if needed.
Exercise
Moderate exercise (150 minutes per week of moderate intensity) supports hormonal balance and healthy body weight. However, very intense or excessive exercise can suppress ovulation by elevating cortisol and reducing oestrogen — so balance is key.
Body Weight
Both underweight and overweight status can disrupt ovulation. A BMI below 18.5 or above 30 is associated with longer time to conception. Even modest weight changes (5–10% of body weight) can restore ovulation in people who have lost it due to weight-related factors.
Stress
Chronic high stress elevates cortisol, which suppresses GnRH (the hormone that initiates the hormonal cascade of the cycle). While it's impossible — and counterproductive — to eliminate all stress, practices like regular physical activity, adequate sleep, and mindfulness have been shown to support hormonal health.
Alcohol and Caffeine
Heavy alcohol consumption is associated with reduced fertility. Current guidance generally recommends avoiding alcohol when trying to conceive, particularly once ovulation has occurred. Caffeine appears safe in moderate amounts (under 200 mg/day, roughly one cup of coffee) but higher intake may be associated with slightly longer time to conception.
Supplements to Consider
- Prenatal vitamin with folate — foundational
- Vitamin D — if deficient
- CoQ10 — some evidence for improving egg quality, particularly in those over 35
- Omega-3 fatty acids — anti-inflammatory support
Common Myths About Conception
- Myth: You can get pregnant any day of the month. Fact: Pregnancy is only possible during the ~6-day fertile window per cycle.
- Myth: Lying down after sex improves chances. Fact: No evidence supports this. Sperm reach the fallopian tubes within minutes.
- Myth: Certain sexual positions improve chances. Fact: No evidence supports this either.
- Myth: You should have sex every day during your fertile window. Fact: Every 1–2 days is sufficient. Daily sex doesn't significantly improve odds and can increase stress.
When to See a Fertility Specialist
The general guidance is to seek evaluation after:
- 12 months of regular, unprotected intercourse if you're under 35
- 6 months if you're 35–39
- 3 months if you're 40 or older
- Sooner if you have known risk factors: irregular or absent periods, PCOS, endometriosis, previous pelvic infections, or if your partner has known fertility issues