Within any given menstrual cycle, healthy couples only have a 25-30 % chance of conceiving, which is why it is critical that couples wishing to conceive ensure that they are doing everything they can to maximise their chances of conceiving. Our eating habits are one of the few factors within our control that impact not only our chances of falling pregnant, but also affect the health of the baby. In general, a healthy diet for optimal fertility follows the Australian Guide to Healthy Eating, which stems from the Australian Dietary Guidelines , however there are a few key foods, nutrients and related factors that women who are wishing to fall pregnant should focus on.
Maintaining a healthy body weight is critical for fertility
Having a healthy body weight and ensuring that food intake is balanced with your physical activity level is an important factor for fertility. Being both underweight and overweight can affect a woman's chance of conceiving and delivering a healthy, normal weight baby. Interestingly, both the male and female's body weight will affect fertility.
Being underweight can:
Reduce reproductive function and hormone production in women;
Decrease sperm production in males;
Increase the chances of having a low birthweight infant, which is associated with poorer health outcomes for the baby.
Being Overweight can:
Cause irregular menstrual cycles/ovulation problems in women;
Iron is a mineral that is found in our red blood cells and helps to carry oxygen around the body. During pregnancy women need more iron as their blood volume increases and the baby's blood is being produced, so more blood means women need more iron to transport more oxygen around the body. Studies have found that infertility is less common in women who conceive an adequate amount of Iron. 
The best source of iron is animal flesh - meat, fish and poultry. Iron is also found in vegetarian sources, such as wholegrains, legumes and certain vegetables such as spinach, but it is not absorbed as well. The Queensland Government Resource on Iron provides a list of the best food sources of iron, and an example eating plan that shows how to ensure you're eating enough iron each day.
Include enough antioxidant rich foods in your diet:
Eat plenty of fruit and vegetables to ensure you are getting enough antioxidants in your diet
Antioxidants protect us from something called oxidative stress, which results from normal bodily processes as well as external factors such as pollution and smoking. Oxidative stress has many negative affects on our body and has been linked to a number of diseases. It has also been associated with infertility as oxidative stress can damage sperm, making it more difficult for the sperm to fuse with the egg. It can also damage the DNA within the sperm, which can result in birth defects for the baby. In women, oxidative stress can damage the eggs and reproductive organs. Luckily, antioxidants can protect us from oxidative stress.
To ensure your diet is rich in antioxidants, make sure you are eating a wide variety of fruits and vegetables each day. The Australian Dietary Guidelines, provides detailed information on how many serves of fruits and veggies you should be eating, and how big a serve is.
Ensure your diet includes an adequate amount of Folate/Folic acid PRIOR to conception:
Folate is a B vitamin that plays a critical role in the early development of the brain and spinal cord of babies growing in the womb. A strong link has been found between an insufficient folate intake by the mother, and defects of the brain and spinal cord in the infant, including the condition Spina bifida.. The key action of folate occurs in the first 4-6 weeks of pregnancy, and because a large percentage of pregnancies are unplanned, many women won't know they are pregnant until it is too late. This is why it is recommended that women of reproductive age ensure they are consuming enough folate, regardless of whether they are attempting to fall pregnant. 
Good Sources of folate include:
Vegetables such as asparagus, spinach and broccoli; Fruits such as strawberries, oranges and bananas;
Commercially sold bread: In Australia, the government has made it mandatory for all commercial bread-flour to be fortified with folic acid, to assist in preventing birth defects in infants. Many other products such as breakfast cereals and juices also have folic acid added to them but always check the label first;
Folic acid supplements: Unlike many other vitamin supplements, folic acid is actually absorbed better by our bodies in supplement form.
For more information of Folate see the Australian Government's Better Health Channel's Folate for Women resource.
Maintain a healthy body weight and ensure you are eating enough food to match your activity levels;
Ensure you are consuming enough iron by choosing lean meat, fish and protein, as well as plant based sources such as wholegrains, legumes and vegetables;
Consume a wide variety of fruit and vegetables to ensure a good intake of antioxidants as well as folate;
Limit your intake of caffeine and alcohol;
Ensure you are consuming enough folate before you attempt to fall pregnant. Choose foods naturally rich in folate as well as foods with added folate such as commercially sold bread, and consider a folate supplement if necessary.