Studies have established that pregnant women have more gingival bleeding and inflammation than women postpartum; these changes are not associated with the amount of plaque. The gingival inflammatory changes begin during the second month of pregnancy and increase in severity until the eighth month of pregnancy  showed that changes in bleeding on probing and periodontal pocket depth increased simultaneously without a relation to plaque between the first and second trimesters and then decreased during subsequent visits. Thus, these changes were reversible, indicating that pregnancy gingivitis does not predispose or proceed to periodontal disease. 

The marginal gingiva and interdental papillae are fiery red and the gingiva is enlarged, mostly affecting the interdental papillae. The gingiva shows an increased tendency to bleed, and in advanced cases, patients sometimes even experience slight pain. During the second and third trimester, the inflammation often becomes more severe. It should be noted that not all women respond in this fashion: in fact, many do not have a clinically altered gingival condition. When there is no dental plaque-associated gingivitis before pregnancy and attentive oral hygiene is monitored, gingivitis usually does not develop. Preventive measures, such as more frequent dental visits for prophylaxis and meticulous plaque control, are therefore indicated for pregnant women. 

Dental plaque is the principal etiologic factor in gingivitis. In periodontal disease, it is well established that the subgingival plaque is characterized by a shift toward a more anaerobic flora. Strong evidence supports the observation that gingival inflammation during pregnancy results from an alteration of the subgingival flora to a more anaerobic state. The anaerobe to aerobe ratio increases significantly during the 13th through 60th week of pregnancy and remains high during the third trimester. It has been shown that increased proportions of Prevotella intermedia are concomitant with an increase in gingivitis and elevated serum levels of estrogen and progesterone in pregnancy. When the proportion of Bacteroides species was monitored in the dental plaque of pregnant women, nonpregnant women, and nonpregnant women taking contraceptives, a 55-fold increase over the control group was noted in the populations of the Bacteroides species in pregnant women and a 16-fold increase in women taking oral contraceptives. This concomitant increase in P. intermedia is most pronounced in the second trimester and correlates with increased gingivitis scores. Subsequent pure culture studies have shown that the marked increase in the proportion of Bacteroides species during pregnancy seems to be associated with increased serum levels of circulating progesterone and estrogens. Both hormones can substitute for naphthoquinone, which is an essential growth factor for P. intermedia. The studies reported to date indicate that female sex hormones may be capable of altering the gingival vascular system, the immune response, and the normal subgingival flora. 

It is prudent, if possible, to wait until parturition for surgical excision of a pregnancy granuloma, unless the lesion is creating a functional problem or appears to be having a deleterious effect on the adjacent periodontium. These lesions may regress after birth; however, surgical excision is usually warranted. The surgery can be accomplished safely throughout pregnancy with the use of local anesthesia and most effectively with the aid of lasers in place of scalpel blades. Lasers have the tendency to reduce the postsurgical  bleeding typically experienced after excision of a pyogenic granuloma. Incomplete excision results in recurrence. A residual fibrous mass may remain if the lesion is large and is allowed to regress postpartum without surgical intervention. 

Gingivitis, or inflammation of the gingiva, is considered to be a reversible process. In contrast, periodontitis results in the loss of tooth attachment (periodontal ligament and alveolar bone) and pocket formation. Though gingivitis is often associated with periodontitis, gingivitis does not usually develop into periodontitis because the putative pathogenic bacteria in periodontitis differ from those associated with gingivitis and because periodontitis is believed to be dependent on different immune mechanisms. A number of investigators have noted sex hormone-mediated alteration of the subgingival flora and the subsequent increase in gingival inflammation. When pregnant and nonpregnant women with periodontitis are compared, however, the differences become less obvious. It has been shown that in contrast to subjects with gingivitis, no significant differences are noted in the total bacterial counts and the proportion of P. intermedia in periodontal pockets of pregnant versus nonpregnant women. Although differences exist in the degree of periodontitis between pregnant and nonpregnant female populations, these reported differences are not impressive. Therefore, conventional approaches for the prevention and treatment of periodontitis are indicated for pregnant patients. 

The hydroxyapatite crystal, of which enamel is made, does not respond to the biochemical and metabolic changes of pregnancy, nor does it respond to changes in calcium metabolism. The belief that morning sickness and vomiting can create an acid pH and therefore increase the decay rate is highly suspect as well. The few seconds that the pH of the oral environment may be lowered is a very brief period of time compared to the months needed for the production of decay. 

A recent study provides strong evidence that the children of mothers with poor self-rated oral health are more likely to grow up to have poorer oral health than those of mothers with good self-rated oral health. Maternal self-rated oral health when children are young appears to be a valid representation of the intricacies of the shared genetic and environmental factors that contribute to oral health throughout the life-course. Unfavorable maternal self-rated oral health should be regarded as a risk indicator for poor oral health among offspring later in life. Simple questions about maternal oral health should form part of a preliminary and inexpensive assessment of a child’s future oral diseases risk (on both clinical and public health grounds). In addition, it is important that mothers are told that their oral health can have an impact on their child’s oral health, and dentists should encourage mothers of young children to receive dental care. 

Ideally a patient’s oral health status should be evaluated and treated by a dentist when pregnancy is anticipated. The evaluation should be comprehensive and identify any potential problem areas (e.g., dental caries, broken teeth and/or restorations, periodontal disease, endodontic involvement). This interceptive approach to treatment is recommended for three reasons: (1) to avoid a dental emergency during pregnancy, which could potentially alter or compromise ideal dental treatment; (2) to reduce the possibility or severity of periodontal disease (e.g., pregnancy granulomas) during pregnancy through instruction and improvement in the patient’s oral hygiene before pregnancy; and (3) to prevent the possibility of a directly negative effect of oral disease on the fetus. The third reason is supported by recent evidence showing that periodontal disease represents a significant risk factor for preterm, low-birth-weight neonates (less than 2500 g). In Offenbacher et al.’s study, pregnant or postpartum mothers were evaluated to determine whether the prevalence of material periodontal infection was associated with the birth of preterm, low-birth-weight infants. It was found that low-birth-weight infants had mothers with significantly worse periodontal disease as compared to mothers of normal birth- weight infants. Additionally, the study showed that expectant mothers with periodontal disease were seven times more likely than others to deliver a preterm, low birth-weight infant. 

Certain drugs occasionally prescribed by dentists are known to cause complications during pregnancy and therefore should be avoided. These include diazepam (Valium), chlordiazepoxide (Librium), flurazepam (Dalmane), meprobamate (Miltown), streptomycin, and tetracycline. Nitrous oxide should not be administered during organogenesis (first trimester), and neither general anesthesia nor intravenous sedation should be used at all during pregnancy. 

However, the limited number of randomized controlled trials prevents us from drawing a solid and clear conclusion. There is definite need for additional well-designed epidemiological studies that will test the hypothesis that periodontal treatment can significantly reduce the rates of certain adverse pregnancy outcomes.