An increased circulating level of these pregnancy hormones is also partly responsible for the magnification of the complex emotions, which you, as a pregnant woman, already have to deal with. The joy of simply being pregnant may be enough to move you to tears. Anxiety regarding how you feel about yourself and the way your body is changing is normal, as are concerns about your health and the health of your developing fetus.
However, overreaction to these, and even simple issues, can be problematic. You may frequently become tearful and find it difficult, or even impossible, to give a reason for your behavior. Recognize that this can be unsettling for your husband too, possibly causing him feelings of confusion and inadequacy. If he feels unable to handle your tears, he may withdraw and ignore the problem, which you may perceive as unloving and non-supportive. Understanding that your behavior is normal will make it far easier for your partner to accept, and may help him be more supportive.
Although your mood swings will be a source of stress to some extent throughout your pregnancy, there's no need for you to suffer increased anxiety over them. Being an expectant mother brings enough to worry about without having to psychoanalyze your ups and downs. Just blame it on the hormones!