I had protected sex, but my period is late – Why?

Almost every woman has experienced a missed period in her life. Not having your period on time can be pretty stressful, especially if you are sexually active – a missed period often is one of the first signs of pregnancy. But what does it mean if you had protected sex and your period is still late

Before you allow stress to take over, you should know there are many reasons a woman can miss a period other than being pregnant. In fact, menstrual irregularities are very common in 14-25% of women during their reproductive years. Today, we will discuss what can cause missing periods and how common they are. 

had protected sex but period is late

How often should you get your period?

During childbearing years, menstruation (periods) usually happens once a month. Menstruation occurs when the uterine lining, which became thicker in the past weeks in preparation for pregnancy, sheds and turns into blood. That is the blood that flows from the uterus through your vagina. Periods tend to last between 3 to 7 days; if you are regular, you will have your period every month or 28 days. 

Can birth control delay my period?

Some birth control options can delay your period or even stop it. For example, emergency contraception (plan B) can make your period late for a few days or weeks. On the other hand, some birth control pills, such as the combination pill, help you have more regular periods. If you are using contraceptive shots, it is normal to miss one or two periods; that tends to vary from one woman to another. So if you had protected sex but your period is late, your birth control method could be the reason. Non-hormonal birth control methods, such as a contraceptive diaphragm or cap, or if your partner uses condoms, shouldn’t affect how often you get your period. 

Does sex delay periods?

There is a belief that sexual activity can delay your period. While sex can cause slight changes to your menstrual cycle, it is rarely the reason behind a delayed or missed period. Another common misconception is that sex can kick-start your period and make it start earlier than expected. Experts agree that having intercourse, even a few days before your period, will not mess with your menstrual cycle timing. If you had unprotected sex recently and are missing your period, you could be pregnant. In that case, you can take a quick home pregnancy test or contact health care providers. 

Why Is My Period Late: 6 Possible Reasons

As mentioned, there are plenty of reasons why you can be experiencing a missed period, even when using a birth control method, such as your partner using condoms or you taking birth control pills. These are the most typical reasons why you had protected sex, but your period is late anyways: 


Stress is one of the most common short-term causes of a missing period. Everyday stress may not be a big deal, but ongoing periods of high-stress levels can impact your menstrual cycle. The hypothalamus is a part of your brain that controls your menstrual cycle. It releases hormones that stimulate your ovaries into secreting estrogen and progesterone – the period-inducing hormones.

The hypothalamus is highly sensitive to external factors, such as stress or anxiety. If stress is throwing off your period, you can try relaxing techniques such as meditation or breathing exercises. Chronic stress can affect other aspects of your health beyond your menstrual cycle. We advise you to contact a mental health care professional if stress is causing problems in your overall health and lifestyle. 

Too much exercise

Intense and excessive exercise sometimes leads the body to release stress hormones known as cortisol. This hormone affects your hypothalamus and disrupts your regular menstrual cycle. That is very common among athletes that practice intense sports or activities.

Low body weight

Individuals with eating disorders like anorexia and bulimia are prone to experience missed periods. Losing too much weight can lead to menstrual cycle irregularities or no periods at all. Body fat plays a crucial role in ovulation; you need at least 22% of body fat to have a regular menstrual cycle. Being underweight – a body mass index lower than 18 – will cause you to stop having periods or having them sporadically. Getting help from a professional healthcare provider and taking your body to an optimal weight will return your periods to their regular length. 


Just like being underweight can affect your period, having excess weight can also alter your menstrual cycle. Excessive fat stores, or adipose tissue, cause the body to secrete too much estrogen. In large quantities, this key hormone for the reproductive cycle can cause irregular periods or may even stop your periods altogether. Women who are obese are also likely to experience other menstrual cycle complications, such as heavy bleeding during their period. Treating obesity and reaching a healthier weight will make your periods return to normal.

Polycystic ovary syndrome (PCOS)

Polycystic ovary syndrome is a condition that affects women during their reproductive years; when you have PCOS, your body produces too much of male hormones called androgens. This hormonal imbalance causes different health issues, like subfertility or irregular periods. Most women with PCOS have fewer than 6 or 8 periods each year. 

Emergency contraception 

If you didn’t use any birth control method during intercourse or just want to be extra sure, emergency contraception is among your birth control options. Also known as the morning-after pill or plan B, it can cause some side effects such as nausea or headache. Another symptom could be a delayed period. The hormones in the morning-after-pill can alter your cycle leading to heavy bleeding or a different duration than usual. Getting your period after taking emergency contraception means you are not pregnant, so being late can cause you a lot of worries. But a delayed period after the plan B is not strange. Nevertheless, if you don’t get your period in about two weeks, you could be pregnant. The next step would be to take a pregnancy test to be sure. 

Can I still get pregnant while using birth control?

Yes, while the chances are extremely low, you can still get pregnant while using protection. As a health care professional or sexual health educator may have explained to you, no birth control method is 100% efficient. And different contraceptive options have different levels of efficacy. The most effective methods are contraceptive implants and the intrauterine device (or IUD). Those methods last many years; fewer than 1 in every 100 women gets pregnant during the first year, making them 99% efficient.

Other birth control options, such as birth control pills, the ring, the patch, or shots, are also highly efficient in preventing pregnancies. However, these methods’ efficacy depends on how rigorous you are with your contraceptive schedule. For example, if you miss a pill, the efficacy levels of the method will significantly drop. Male condoms are 98% efficient when used correctly; if you misuse them, efficacy can drop to 85%. Condoms can also lose most of their efficacy if you use them beyond their expiration date or if they break while having intercourse.

What should I do if my period is late?

Above, we discussed the different reasons why you could have protected sex, but your period is still late. As long as you use contraceptives, you probably don’t have to worry about your period being a couple of days late. Irregularities in the menstrual cycle’s timing are typical in most women; generally, it’s not a reason to be concerned. If you are going through a stressful week, your period will likely start once you reduce your stress levels. Nevertheless, when your period is weeks late, that could be caused by some of the other reasons we mentioned. If you are missing your period due to a medical condition, such as PCOS, or a weight-related condition, we recommend you seek professional help. 

To clear any doubts, you can always take a home pregnancy test if your period is a few weeks late. You can purchase a urine test at any pharmacy; they are easy and quick to use. If you suspect you could be pregnant, a blood pregnancy test at a women’s health and abortion clinic will always be more accurate than a home test. Healthcare professionals will also be able to help you with the next steps you decide to take in case the results are positive.

Are you worried about delayed periods? Contact us now!

Being a few days or a week late shouldn’t be enough reason to worry. Did you have protected sex, but your period is late? You can check the above list of possible reasons why your period has still not arrived. If you suspect you could be pregnant or have any other doubts, don’t hesitate to contact us. Our dedicated team can assess your situation and offer the guidance you need.