As we're talking about the first month of pregnancy, it's probably quite important to define what the "first month of pregnancy" actually means.

Surprisingly, most women (and this included myself!) don't realise exactly when their first month is, until they have discovered that they are pregnant and are sitting at the doctors having their due date calculated!

To measure how many weeks pregnant you are, the convention is to count the number of weeks since your last menstrual period. This means that when people talk about the first month of pregnancy they are effectively talking about the two weeks before you conceived and the two weeks after you conceived. So although you're officially "one month pregnant", you've only actually been pregnant for two weeks! Confusing or what?

This strange convention is used because most people can't be 100% sure of their date of conception, and this method at least provides a standard starting point. Despite only having been pregnant for two weeks, by the end of your first month, you may well have experienced one or more pregnancy symptom!

However, as many early pregnancy symptoms are very similar to pre-menstrual symptoms, it can sometimes be impossible to tell during that first month whether you're heading for your period or are indeed pregnant. So until you take a pregnancy test, this can be a time of uncertainty.

Like any month of pregnancy, this first one differs greatly from woman to woman.

And the timing of that first pregnancy symptom is also vastly different between women, and indeed, for every pregnancy.

At conception? Some women claim to have felt conception, either as a pain or as some other sensation. (This is disputed by the medical profession, but who can say for sure?)

One week after conception? The first sign for some can be as early as one week after conception, when you might notice some very light bleeding, known as "spotting". This is caused by the fertilised egg implanting in the lining of the uterus, and is often mistaken for a period, especially as it can be accompanied by mood swings, cramping and breast tenderness; although it is usually noticably lighter.

At the end of month one? The time when many people start to suspect that they might be pregnant is when they've missed a period. This is often the first symptom of pregnancy.

Months into the pregnancy? (perhaps even nine months...) However, some women may not experience any symptoms at all during the first month. And it is possible, particularly if you have irregular periods, to go several months without even realising that you're pregnant! In rare cases, unsuspecting women have discovered that they are pregnant after being admitted to the emergency ward with mysterious stomach pains...

The pregnancy symptoms that you may experience during the first month are numerous and varied. In addition to possible spotting and a missed period, they can include any of the symptoms typical of the first trimester, as well as symptoms usually associated with pre-menstruation.

Many of these symptoms are caused by the pregnancy hormones which are released in the mother's body from the time when the embryo implants itself into her uterus, and this is why some women feel symptoms so early.

Here is a menu of possible symptoms that you may or may not have during this time:

• Spotting - light, implantation bleeding.
• Mood swings - as these may come just at the time when you're expecting your period, they are often not recognised as a pregnancy sign.
• Breast tenderness - this may be more extreme than before your period, but again, can be rather a confusing symptom. You might also notice visible veins on your breasts and your nipples becoming darker.
• Stomach cramps - as with breast tenderness, these might be worse than normal pre-menstrual cramps, and may go on for longer than normal. Together with a late period this might well signify pregnancy, but not always.
• "Feeling pregnant" - sometimes you just know!
• Tiredness - your body is working extremely hard to develop your baby.
• Frequent urination - caused by your kidneys having to work harder to process the extra body fluid accumulated during pregnancy, and also an effect of the hCG pregnancy hormone. (Later on, this is caused by the baby putting pressure on your bladder).
• Morning sickness or nausea - and as you may have heard, this is often not just confined to the morning..
• Food cravings and aversions - most people have heard about food cravings in pregnancy, but foods that you've always loved might also suddenly become repulsive to you.
• Heartburn - in early pregnancy this is thought to be caused by the hormone progesterone. (Later on it is caused by the baby putting pressure on your abdomen).
• Constipation - this is also caused by progesterone, a muscle-relaxing hormone, useful when it comes to giving birth, but a pain when it also acts on intestinal muscles and slows things down a little too much!
• Feeling faint - this can also be caused by progesterone, which can also relax your blood vessels, causing blood pressure to drop and dizziness or fainting to occur.
• Increased hunger - often described as "incredible" hunger; you're eating for two remember, even if one of you is very very small!
• Heightened sense of smell - it's not known for certain why this happens but one theory is hormones (again!); this time oestrogen, which also rises during pregnancy.
• Headaches - there are many reasons for headaches during the first month of pregnancy; stress may be one of them, hormones can also be a factor, as can the increased volume of blood that pregnancy brings about.
• Backache - particularly low backache; again, caused by more negative effects of that pesky progesterone hormone, this time by loosening the ligaments around your pelvis which can result in instability and pain.
• Thrush - this is an unfortunate symptom, brought about by pregnancy hormones altering the natural balance of bacteria in the vagina. For some women this is a very early pregnancy sign.
• Missed period - some women may mistake spotting for their period, and this can sometimes lead to confusion with their due date!

Although these are common first month pregnancy symptoms, it's important to be aware that they may not necessarily indicate pregnancy. As well as premenstrual symptoms, they could be signs of other medical conditions or the result of factors like a change in a your diet or stress. So at this early stage even if you are experiencing symptoms, it may be unwise to conclude that you are pregnant until you've had a positive pregnancy test. That's the only way to be 100% certain.

If at the end of month one you do discover that you're pregnant, and you have already experienced some or many of these symptoms, it may be a bit depressing to think that you still have another 36 weeks to go! However, be assured that for most people, some of these symptoms (particularly morning sickness, mood swings and tiredness) will gradually ease off by the beginning of your second trimester. And console yourself with the fact that the second trimester is meant to be a time of renewed energy and a general feeling of wellbeing!

...And even if that's not the case for you, pregnancy doesn't last forever and it will all be worth it in the end!

(1) http://commons.wikimedia.org/wiki/Image:Pregnancy_test_result.jpg