Yes! Any time a woman has vulnerable coitus, she could get pregnant but not always. 

WHAT IS AN IRREGULAR PERIOD? 

A regular standard menstrual cycle occurs every 28 days. An irregular menstrual cycle occurs more frequently than 21 days or as late as >35 days. Irregular periods can come early, be missed, or stay longer than 8 days. 

Irregular Periods & Pregnancy-In case of Irregular periods if you are ovulating then chances of pregnancy if there. Ovulation is the process of release of an egg from the ovaries. 

It's the time when a female conceives. A girl with an irregular menstrual cycle many time still ovulates, but not on a regular, predictable schedule but 2 weeks prior to her coming period. 

Women with irregular menstruation may ovulate at different points from cycle to cycle. That makes it insolvable for a girl to know when she's most fertile. 

Irregular menstrual cycles also can make it hard for a woman to know if she's pregnant or not since she does not know when to anticipate her period. 

Many times we have seen a female who is 3 months pregnant but she is not aware of this, due to irregular menstruation. Having vulnerable coitus or coitus in an unsafe period makes you vulnerable to getting pregnant & also could also get an STD, similar to chlamydia, genital knobs, or HIV. 

The only way to fully help gestation and STDs is abstinence ( not having coitus) or using condoms for protection. Use a condom every time to cover against unplanned gestation and STDs, If you do coitus. For added protection, numerous couples use condoms along with another system of birth control, like birth control capsules or an IUD. 

THE CAUSES OF IRREGULAR PERIODS- 

  1. PCOS/PCOD- One of the very common causes of an irregular menstrual cycle is Polycystic Ovary Syndrome (PCOS). PCOS is the disturbance in the hormones, which controls the reproductive system. PCOS causes irregular ovulation, cysts on ovaries, bleeding, and infertility. Thyroid Issues- Thyroid disturbance also disturbs the menstrual cycle if not treated properly.
  2. Fibroids- Fibroids may be one or several. Which may range from as small as an apple seed to the size of a grapefruit. These tumors are not cancerous, but they may cause excessive bleeding and pain during periods
  3. Endometriosis- The endometrial tissue is the innermost lining of the uterus that sheds down every month & discharged with the menstrual blood. Endometriosis occurs when the endometrial tissue starts to grow outside the uterus. 
  4. Uterine polyp- Uterine polyps are small growths in the endometrial lining of the uterus. Uterine fibroids are non-cancerous tumors that attach to the wall of the uterine lining. 
  5. Pelvic Inflammatory disease ( PID )- Pelvic inflammatory disease is an infection of bacteria that affects the women's reproductive organs including the vagina. Bacteria may enter the vagina through sexual contact and then may spread to the uterus and upper genital organs.
  6. Stress and lifestyle factors- Gaining or losing weight, dieting, changes in exercise routines, travel or illness in a woman's day-to-day routine can have an impact on her menstrual cycle.Birth control pills- Birth control pills have a combination of estrogen and progestin. These pills prevent pregnancy by keeping the ovaries from releasing eggs. If you stop pills on or off then this can disturb menstruation.
  7. Premature ovarian insufficiency