Hii,
Full history is needed .
There are so many reasons for that for example ,ovulation issues, hormonal issues, semen or sperm issues, age factor, timing , if you are on any medications and so on...
To rule out the cause and finding out the solution ,You have to consult a doctor or a gynaecologist.
Next Steps
Do sonography, TFT, semen analysis etc investigations.
Health Tips
Be stressfree
Be physically and mentally active
Improve lifestyle pattern
Do yoga
Do meditations