Caloric
 intake must be increased, to ensure proper development of the fetus. 
The amount of weight gained during pregnancy varies among women. The National Health Service recommends
 that overall weight gain during the 9 month period for women who start 
pregnancy with normal weight be 10 to 12 kilograms (22–26 lb). During pregnancy, insufficient weight gain can compromise the health of the fetus. Women with fears of weight gain or with eating disorders may
 choose to work with a health professional, to ensure that pregnancy 
does not trigger disordered eating. Likewise, excessive weight gain can 
pose risks to the woman and the fetus. Women who are prone to beingoverweight may choose to plan a healthy diet and exercise to help moderate the amount of weight gained.
Immunological tolerance/ Pre-eclampsia
Research
 on the immunological basis for pre-eclampsia has indicated that 
continued exposure to a partner's semen has a strong protective effect 
against pre-eclampsia, largely due to the absorption of several immune 
modulating factors present in seminal fluid. Studies also showed that 
long periods of sexual cohabitation with the same partner fathering a 
woman's child significantly decreased her chances of suffering 
pre-eclampsia. Several other studies have since investigated the 
strongly decreased incidence of pre-eclampsia in women who had received 
blood transfusions from their partner, those with long, preceding 
histories of sex without barrier contraceptives, and in women who had 
been regularly performing oral sex, with one study concluding that 
"induction of allogeneic tolerance to the paternal HLA molecules of the fetus may be crucial. Data collected strongly suggests that exposure, and especially oral exposure to soluble HLA from semen can lead to transplantation tolerance."
Other
 studies have investigated the roles of semen in the female reproductive
 tracts of mice, showing that "insemination elicits inflammatory changes
 in female reproductive tissues,"concluding that the changes "likely 
lead to immunological priming to paternal antigens or influence 
pregnancy outcomes." A similar series of studies confirmed the 
importance of immune modulation in female mice through the absorption of
 specific immune factors in semen, including TGF-Beta, lack of which is also being investigated as a cause of miscarriage in women and infertility in men.
According
 to the theory, pre-eclampsia is frequently caused by a failure of the 
woman's immune system to accept the fetus and placenta, which both 
contain "foreign" proteins from paternal genes. Regular exposure to the 
father's semen causes her immune system to develop tolerance to the 
paternal antigens,
 a process which is significantly supported by as many as 93 currently 
identified immune regulating factors in seminal fluid. Having already 
noted the importance of a woman's immunological tolerance to
 the fetus's paternal genes, several Dutch reproductive biologists 
decided to take their research a step further. Consistent with the fact 
that human immune systems tolerate things better when they enter the 
body via the mouth, the Dutch researchers conducted a series of studies 
that confirmed a surprisingly strong correlation between a diminished 
incidence of pre-eclampsia and a woman's practice of oral sex, and noted
 that the protective effects were strongest if she swallowed her 
partner's semen. The researchers concluded that while any exposure to a 
partner's semen during sexual activity appears to decrease a woman's 
chances for the various immunological disorders that can occur during 
pregnancy, immunological tolerance could
 be most quickly established through oral introduction and 
gastrointestinal absorption of semen.Recognizing that some of the 
studies potentially included the presence of confounding factors, such 
as the possibility that women who regularly perform oral sex and swallow
 semen might also engage in more frequent vaginal intercourse, the 
researchers also noted that, either way, the data still overwhelmingly 
supports the main theory behind all their studies--that repeated 
exposure to semen establishes the maternal immunological tolerance necessary for a safe and successful pregnancy.
Drugs in pregnancy
Drugs
 used during pregnancy can have temporary or permanent effects on the 
fetus. Therefore many physicians would prefer not to prescribe for 
pregnant women, the major concern being over teratogenicity of
 the drugs. This results in inappropriate treatment of pregnant women. 
Use of drugs in pregnancy is not always wrong. For example, high fever 
is harmful for the fetus in the early months. Use of paracetamol is better than no treatment at all. Also, diabetes mellitus during pregnancy may need intensive therapy with insulin.
 Drugs have been classified into categories A,B,C,D and X based on the 
Food and Drug Administration(FDA) rating system to provide therapeutic 
guidance based on potential benefits and fetal risks. Drugs like multivitamins that
 have demonstrated no fetal risks after controlled studies in humans are
 classified as Category A. On the other hand drugs like thalidomide with proven fetal risks that outweigh all benefits are classified as Category X.
Sexuality during pregnancy
Most pregnant women can enjoy sexual intercourse throughout
 gravidity. Most research suggests that, during pregnancy, both sexual 
desire and frequency of sexual relations decrease. In context of this 
overall decrease in desire, some studies indicate a second-trimester 
increase, preceding a decrease. However, these decreases are not 
universal: a significant number of women report greater sexual 
satisfaction throughout their pregnancies.
Sex
 during pregnancy is a low-risk behaviour except when the physician 
advises that sexual intercourse be avoided, which may, in some 
pregnancies, lead to serious pregnancy complications or health issues 
such as a high-risk for premature labour or a ruptured uterus. Such a 
decision may be based upon a history of difficulties in a previous 
childbirth.
Some
 psychological research studies in the 1980s and '90s contend that it is
 useful for pregnant women to continue to have sexual activity, 
specifically noting that overall sexual satisfaction was correlated with
 feeling happy about being pregnant, feeling more attractive in late 
pregnancy than before pregnancy and experiencing orgasm. Sexual
 activity has also been suggested as a way to prepare for induced 
labour; some believe the natural prostaglandin content of seminal liquid
 can favour the maturation process of the cervix making it more 
flexible, allowing for easier and faster dilation and effacement of the 
cervix. However, the efficacy of using sexual intercourse as an 
induction agent "remains uncertain".
During
 pregnancy, the fetus is protected from penetrative thrusting by the 
amniotic fluid in the womb and by the woman's abdomen.
Abortion
An abortion is
 the removal or expulsion of an embryo or fetus from the uterus, 
resulting in or caused by its death. This can occur spontaneously or 
accidentally as with a miscarriage, or be artificially induced by medical, surgical or other means.